Article 81 — Suspension of proceedings

Article 81 is a coordination rule for situations in which closely connected GDPR proceedings are pending before courts in different EU Member States. Its purpose is to reduce duplication, save judicial resources and, most importantly, avoid courts issuing judgments that cannot sensibly coexist.

In simple terms:

If courts in different Member States are dealing with the same controller or processor and essentially the same processing dispute, they must communicate. The court approached later may pause its case and, in narrower circumstances, may give up the case so that the disputes can be heard together before the court approached first.

Article 81 does not automatically transfer every later case to the first court. It creates a graduated system:

1. Communication is mandatory under paragraph 1.
2. Suspension is discretionary under paragraph 2.
3. Declining jurisdiction is possible only under strict conditions under paragraph 3.

The official text confirms this progression from mandatory court-to-court contact to optional suspension and, finally, possible relinquishment of jurisdiction.

1. Why Article 81 is necessary

The GDPR deliberately allows certain proceedings to be brought in more than one Member State. Under Article 79, for example, a data subject may generally sue:

• where the controller or processor has an establishment; or
• where the data subject habitually resides.

A single Europe-wide processing system may therefore generate cases in several Member States.

Illustration

A social-media platform headquartered in Ireland uses the same behavioural advertising system throughout the EU. Proceedings are brought:

• in France by a French user seeking an injunction;
• in Germany by a consumer organisation challenging the same consent design;
• in Ireland by the controller challenging a connected regulatory decision. If every court acts without knowing about the others, one court might decide that the consent system is valid while another decides that the same system is unlawful. A third might order the system to stop across Europe while the first permits it to continue. Article 81 is designed to reduce that danger. It does not require universal centralisation of GDPR litigation. Individuals retain access to courts under Articles 78 and 79. Instead, Article 81 introduces procedural coordination after overlapping proceedings arise.

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2. Article 81 is about pending court proceedings

The Article applies where proceedings are pending before courts in different Member States.

It does not directly regulate:

• two complaints pending before supervisory authorities;
• a purely internal company grievance;
• two cases before courts within the same Member State;
• parallel administrative investigations with no court proceedings;
• proceedings in a non-EU country.

Illustration

A complaint is pending before the French supervisory authority while a court case is pending in Germany. Article 81 does not directly apply merely because those two processes overlap. One is regulatory and the other is judicial. However, other rules may coordinate them, including:

• supervisory cooperation under Articles 60 to 66;
• national procedural rules;
• Article 77 to 79 case law concerning parallel remedies. If the French supervisory decision is later challenged before a French court, and the connected German judicial proceeding remains pending, Article 81 may become relevant. Proceedings in the same Member State If substantially overlapping cases are pending before two courts in Italy, Article 81 does not govern their coordination because paragraph 1 requires a proceeding in another Member State. Italian procedural law would determine whether the cases should be:

• consolidated;
• transferred;
• stayed;
• assigned to the same court;
• resolved through domestic lis pendens rules.

Article 81 deals specifically with cross-border judicial duplication.

3. Does Article 81 apply to both Articles 78 and 79?

This is one of the Article’s main interpretive difficulties.

Recital 144 begins with a court handling proceedings against a decision of a supervisory authority. That language points toward Article 78 proceedings. But Article 81 itself is not expressly limited to Article 78.

Its operative text refers more broadly to proceedings concerning:

“the same subject matter as regards processing by the same controller or processor.”

The wording therefore supports application to proceedings under both:

• Article 78, judicial review of a supervisory authority;
• Article 79, direct proceedings against a controller or processor.

A broad interpretation also fits the Article’s purpose. Conflicting judgments may arise between:

• two Article 79 cases;
• an Article 78 case and an Article 79 case;
• two Article 78 cases connected with the same processing.

The commonly presented commentary likewise recognises substantial support for the broader approach, while acknowledging disagreement.

Illustration: two Article 79 cases

A French user sues a platform in France over its advertising profile. A German user sues the same platform in Germany over the same profiling architecture. Article 81 may assist coordination even though neither case challenges a supervisory decision.

[!example] Illustration: Article 78 and Article 79 A controller challenges an Irish supervisory authority’s finding that its consent banner is unlawful. At the same time, users sue the controller in Germany seeking an injunction against that same banner. The parties and remedies differ, but the cases may require contradictory answers to the same central question: whether the consent process complies with the GDPR. Recital 144 cannot silently narrow the Article Recitals help interpret legislation but do not replace its operative text. Recital 144 provides especially helpful context for related proceedings and irreconcilable judgments, but it should not be used to insert an Article 78-only limitation that Article 81 does not state. The better approach is functional: Does the cross-border litigation concern the same processing by the same controller or processor and create a real risk of incompatible judgments?

4. Article 81 and public-sector proceedings

The supplied commentary says Article 81 is confined to the private sector. That is too categorical.

Article 79 limits the habitual-residence forum where a Member State public authority acts in the exercise of public powers. This often means that proceedings against such an authority will be concentrated in that authority’s own Member State.

But Article 81 does not expressly exclude public bodies.

Illustration

A public university acts as a controller while providing ordinary paid online educational services across several Member States. Depending on the facts, it may not be exercising distinctive sovereign powers in that processing operation. Cross-border proceedings may still arise. Likewise, a public body may act:

• through public powers for one processing operation;
• commercially or operationally for another. The analysis must be activity-specific. Article 81 may be less frequently relevant to sovereign public-authority processing, but it is not textually a private-sector-only rule.

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5. Paragraph 1: Mandatory communication between courts

Article 81(1) provides that where a competent court has information about relevant proceedings pending in another Member State, it shall contact the other court to confirm their existence.

The word “shall” creates a duty.

Once the necessary threshold is met, the court cannot simply ignore the information and continue without inquiry.

The purpose of contact is initially limited: to confirm whether connected proceedings genuinely exist. The court should not decide suspension based only on:

• rumours;
• incomplete party assertions;
• a press report;
• an unverified docket reference.

Illustration

A controller tells the Spanish court: “A similar case may be pending in the Netherlands.” The Spanish court obtains enough information to believe the report may be genuine. It should contact the Dutch court to confirm:

• whether proceedings exist;
• when they began;
• which parties are involved;
• which processing is challenged;
• what relief is sought;
• what procedural stage has been reached. Only then can the Spanish court decide whether paragraph 2 or 3 is relevant.

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6. When does the duty to contact arise?

The court must have information indicating that qualifying proceedings are pending elsewhere.

The Article does not require every GDPR court to search all EU court databases before taking any step. But once credible information emerges, the court must act.

Information may come from:

• a party;
• an intervener;
• a supervisory authority;
• a representative organisation;
• a public judgment or docket;
• another court;
• documents in the case file.

Illustration

The claimant’s pleading itself states that a representative organisation has brought a related action in Belgium. The national court cannot disregard the statement simply because neither party formally requested suspension. Paragraph 1’s communication duty is directed to the court. How much information is enough? Absolute certainty is unnecessary because the purpose of contact is to verify the proceedings. But a purely speculative assertion may be insufficient. A practical threshold is whether the information gives the court a reasonable basis to suspect that:

1. judicial proceedings are pending;
2. they are in another Member State;
3. they concern the same controller or processor;
4. they concern materially overlapping processing.

7. What should the courts communicate?

Article 81 does not prescribe a standard form. Useful information may include:

• parties;
• defendant controller or processor;
• identity of the relevant corporate entity;
• date the court was seized;
• processing operation;
• legal claims;
• remedies requested;
• territorial scope;
• current stage;
• jurisdictional position;
• whether consolidation is legally possible.

Communication must respect:

• judicial independence;
• confidentiality;
• personal data protection;
• party rights;
• applicable national procedural rules.

Illustration

The first case contains medical information about claimants. The courts need not exchange full health files merely to determine whether the disputes overlap. Initially, they may exchange:

• anonymised case descriptions;
• claim summaries;
• dates;
• processing categories;
• requested relief. Data minimisation remains relevant even in judicial coordination.

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8. “Same controller or processor”

Article 81 requires processing by the same controller or processor.

This condition may appear simple where the identical legal entity is named in both proceedings.

Illustration

Both cases are brought against Platform Ireland Ltd concerning the same recommendation engine. The same-entity requirement is readily satisfied. The question becomes harder within corporate groups.

Illustration

The French case names Platform France SAS. The Irish case names Platform Ireland Ltd. Both concern one Europe-wide advertising system. The companies belong to the same group, but they are not automatically the same controller. The court must examine whether:

• one entity is wrongly named;
• both jointly determine the processing;
• one is merely an establishment of the relevant controller;
• each controls a different processing stage;
• one acts as processor for the other. Corporate affiliation alone does not make separate entities the “same controller.” Joint controllers Suppose two entities jointly determine the relevant purposes and essential means. A case against Joint Controller A and a case against Joint Controller B may create a strong risk of inconsistent decisions. But Article 81 literally refers to the “same controller or processor.” Whether the Article reaches proceedings against different members of one joint-controllership arrangement is uncertain.

A purposive interpretation may support coordination where both cases concern the same jointly determined operation. Yet courts should not erase the legal distinction between entities. Other mechanisms, including Brussels I Recast related-action rules and national case management, may assist where Article 81’s exact identity requirement is disputed.

9. “Same subject matter”

The GDPR does not define “same subject matter.”

Recital 144 explains that proceedings are related where they are so closely connected that hearing them together is expedient to avoid irreconcilable judgments.

This indicates a broader concept than strict identity of:

• claimant;
• legal claim;
• remedy;
• amount;
• procedural form.

The focus is on the processing dispute and the risk of incompatible outcomes.

Strong case of the same subject matter

• Same platform.
• Same consent interface.
• Same tracking technology.
• Same processing purposes.
• One case seeks an injunction.
• The other challenges a regulatory finding concerning that interface.

The remedies differ, but the central legal and factual question is the same.

Weak case

• One case concerns payroll data.
• Another concerns customer CCTV.
• The defendant is the same company.
• The processing operations, data subjects, purposes and legal issues are unrelated.

The same defendant is not enough.

Relevant factors

Courts should consider:

• data involved;
• category of data subjects;
• purpose;
• processing operation;
• system or technology;
• time period;
• lawful basis;
• alleged infringements;
• geographic scope;
• requested remedies;
• practical compatibility of judgments.

[!example] Illustration One court is asked to declare a facial-recognition system lawful. Another is asked to prohibit its use because it lacks an Article 9 condition. Those judgments would be difficult to reconcile. By contrast, one court deciding whether a user received a late access response does not necessarily conflict with another court considering the platform’s general data-retention architecture.

10. Same subject matter does not require the same plaintiffs

Article 81 does not say that the parties must be identical. It requires overlapping processing by the same controller or processor.

Different data subjects may challenge a common system.

Illustration

A Polish employee challenges an automated productivity score. A Czech employee separately challenges the same scoring system operated by the same employer. The data subjects are different, but the cases may concern the same:

• algorithm;
• data categories;
• purpose;
• legal basis;
• automated decision-making practice. This differs from strict lis pendens under Article 29 of Brussels I Recast, which addresses the same cause of action between the same parties and requires the later court to stay proceedings. Article 30 of Brussels I Recast instead addresses related actions and gives later courts discretion to stay or, under conditions, decline jurisdiction. Article 81 more closely resembles this related-actions model.

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11. “Pending” proceedings

Article 81 applies only while the other proceeding is pending.

A case is generally pending once the court has been properly seized under the applicable procedural rules.

The GDPR does not define the precise moment. Article 32 of Brussels I Recast offers a useful model: a court is ordinarily treated as seized when the initiating document is lodged, provided the claimant completes required service steps, or, in systems requiring prior service, when the responsible service authority receives the document.

Illustration

A claimant privately drafts a complaint but has not filed or served it. The proceeding is not yet pending. If the claim has been properly lodged and necessary service steps are being followed, pendency may exist even before the first hearing. Final judgment If the earlier proceeding has ended in a final judgment, Article 81’s suspension mechanism may no longer apply because the case is no longer pending. Other rules then become relevant, including:

• recognition;
• enforcement;
• res judicata;
• evidential effect;
• Brussels I Recast.

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12. Identifying the court first seized

Paragraphs 2 and 3 distinguish:

• the court first seized;
• every later court.

The filing sequence matters.

Illustration

The French court was seized on 1 March. The German court was seized on 5 March. The German court is the later court and may use Article 81(2) or, if the conditions are satisfied, Article 81(3). The first court does not suspend under Article 81 merely because a later case exists. Simultaneous filings If filings occur at nearly the same time, courts should establish the exact legally relevant timestamps under the applicable rules. The supplied commentary suggests that if proceedings are pending “at the same time,” neither court may suspend. That is too absolute. Modern filing systems normally permit identification of sequence. Even where exact simultaneity occurs, courts should seek a practical solution through:

• court-to-court communication;
• national rules;
• related-action principles;
• agreement of parties;
• procedural economy. Article 81 should not become unusable because two filings occurred on the same calendar day.

13. Paragraph 2: Discretionary suspension

Once the courts confirm qualifying parallel proceedings, any competent court other than the first seized may suspend its proceedings.

The word “may” is crucial.

Suspension is not automatic.

The later court must exercise judgment based on:

• overlap;
• stage of each proceeding;
• risk of incompatible judgments;
• speed of the first case;
• availability of interim relief;
• claimant interests;
• procedural economy;
• scope of the requested remedies;
• Article 47 right to timely judicial protection.

Illustration

favouring suspension The Irish proceeding is close to final judgment and concerns the legality of a Europe-wide consent mechanism. A later German proceeding raises the same central issue.

Suspension may:

• avoid duplicate expert evidence;
• reduce costs;
• permit the Irish legal interpretation to be considered;
• prevent inconsistent injunctions.

Illustration

against suspension The first case is progressing extremely slowly and concerns only damages for one historical event. The later case seeks an urgent injunction to prevent publication of children’s location data. Suspension could expose children to continuing harm. The later court may properly continue and grant appropriate protection.

14. Suspension is not dismissal

A suspended case remains pending.

The court temporarily pauses some or all procedural steps. It does not permanently give up jurisdiction.

During suspension, the later court may need to:

• monitor the first case;
• preserve evidence;
• maintain interim measures;
• request updates;
• determine when to resume;
• protect limitation positions.

Illustration

A Spanish court suspends a claim pending the outcome of a Belgian case. The Belgian case later ends because the claimant withdraws. The Spanish court may lift the stay and continue. The Spanish claimant has not lost the action merely because it was suspended. Partial suspension Where only one issue overlaps, the court should consider whether it can stay only that part.

Illustration

The later claim raises:

1. validity of a consent mechanism;
2. separate failure to answer an access request.

The first proceeding concerns only consent.

A complete suspension may be unnecessary. The later court might pause the consent issue while continuing the access claim, if national procedure permits.

Proportional case management is preferable to an unnecessarily broad stay.

15. Factors relevant to suspension

Risk of irreconcilable judgments

This is the central factor identified by Recital 144.

Judgments are not irreconcilable merely because they use different reasoning. The concern is that compliance with one result would undermine or contradict the other.

Illustration

Court A orders the controller to continue preserving a database for litigation. Court B orders immediate deletion of the same database. The orders produce a direct practical conflict. Progress of the first case A stay is more attractive where the first court is close to judgment. A stay may be less attractive where:

• jurisdiction is disputed;
• service has not occurred;
• the proceeding is dormant;
• delay is extreme. Urgency and harm A case seeking urgent protection may need to continue despite overlap.

Procedural scope

The first case may not be able to resolve all issues raised in the later action.

Rights of different data subjects

The interests of one claimant should not automatically be sacrificed to litigation controlled by another claimant in another country.

16. Article 47 and excessive delay

Suspension must remain compatible with the right to an effective remedy within a reasonable time.

Illustration

A later court suspends proceedings indefinitely because a related foreign case exists. The first case remains inactive for five years. The stay may become disproportionate. The later court should review suspension periodically and ask:

• Is the earlier case progressing?
• Does it still concern the same issues?
• Is judgment expected?
• Is the claimant suffering continuing harm?
• Can part of the case proceed?
• Are interim measures needed? A stay lawful at the beginning may become unlawful through excessive duration.

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17. Paragraph 3: Declining jurisdiction

Paragraph 3 goes further than suspension.

A later court may give up jurisdiction so that the actions can be consolidated before the first court.

This is a stronger and potentially final step. Therefore, four cumulative conditions apply:

1. the proceedings must be pending at first instance;
2. a party must apply for the later court to decline jurisdiction;
3. the first court must have jurisdiction over the actions in question;
4. the first court’s law must permit consolidation.

Even when these conditions are satisfied, the later court may, rather than must, decline jurisdiction.

18. First-instance requirement

Declining jurisdiction is available only where the proceedings are pending at first instance.

The reason is procedural fairness and practicality. Consolidation becomes much more difficult once:

• one case is on appeal;
• evidence has been heard;
• factual findings have been made;
• different standards of appellate review apply.

[!example] Illustration A French case is before the first-instance court. A related German case is also at first instance. Article 81(3) may be considered. If the French case is already before the final appellate court, the later German court cannot rely on paragraph 3 to transfer its first-instance action into that appellate process. Paragraph 2 suspension may still be considered.

19. Application by a party is mandatory

Unlike paragraph 2, paragraph 3 requires an application by one of the parties.

The court cannot ordinarily decline jurisdiction under Article 81(3) entirely on its own initiative.

Illustration

The controller asks the German court to decline jurisdiction in favour of the French court first seized. The German court may assess the paragraph 3 conditions. If neither party asks, the German court may still consider suspension under paragraph 2, but the specific paragraph 3 route is unavailable. This requirement protects parties from unexpectedly losing their chosen forum without an opportunity to address transfer and consolidation.

20. The first court must have jurisdiction over all relevant actions

The first court must have jurisdiction not only over its existing action but also over the action pending before the later court.

Illustration

A Belgian data subject sues a controller in Belgium based on habitual residence. A German organisation brings a different representative action in Germany. Before the German court declines jurisdiction, it must be satisfied that the Belgian court could validly hear the representative action too. If the Belgian court lacks jurisdiction over that type of claim or defendant, declining jurisdiction would not produce consolidation. It would merely deprive the claimant of a forum. The later court may need reliable information about:

• jurisdictional basis;
• parties;
• causes of action;
• defendant establishments;
• representative standing;
• limits of the first court’s powers. Court-to-court communication is therefore practically important beyond the initial confirmation required by paragraph 1.

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21. Consolidation must be permitted by the first court’s law

The first-seized court’s national law must allow the actions to be consolidated.

This is a major limitation.

Different Member States have different rules concerning:

• joinder;
• group claims;
• representative actions;
• transfer of proceedings;
• amendment of pleadings;
• intervention;
• judicial competence.

Illustration

The first court has jurisdiction over both claims but its procedural law does not permit claims initiated in another Member State to be consolidated in the proposed manner. The later court cannot decline jurisdiction under Article 81(3). It may instead suspend under paragraph 2. “Decline jurisdiction” is not itself consolidation A later court’s withdrawal does not magically move the case file to the first court. The party may need to:

• bring or refile the claim before the first court;
• join the existing proceeding;
• satisfy procedural requirements;
• comply with limitation rules;
• pay applicable fees. Before declining, the later court should consider whether the claimant will genuinely be able to pursue the case before the first court.

Otherwise, the claimant could lose access to justice.

22. Discretion even when all conditions are met

Paragraph 3 says the later court may decline jurisdiction.

It should consider:

• fairness;
• procedural economy;
• delay;
• language;
• costs;
• evidence;
• claimant vulnerability;
• availability of interim protection;
• stage of proceedings;
• scope of consolidation;
• limitation risks.

Illustration

The first court technically permits consolidation, but:

• the proceeding is nearly dormant;
• the individual would face prohibitive translation and representation costs;
• urgent protection is not available there;
• the later court has already heard most evidence. The later court may decide not to decline jurisdiction. Consolidation is a tool for good administration, not an end in itself.

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23. Relationship with Brussels I Recast

Article 81 resembles Article 30 of Brussels I Recast, which governs related actions in different Member States. Under Article 30:

• a later court may stay related proceedings;
• it may, under conditions, decline jurisdiction where the first action is at first instance and consolidation is possible;
• actions are related where hearing them together is expedient to avoid irreconcilable judgments.

By comparison, Article 29 of Brussels I Recast applies more strictly where:

• the cause of action is the same;
• the parties are the same.

In that situation, the later court must stay and eventually decline jurisdiction once the first court’s jurisdiction is established.

Article 81’s discretionary model is therefore closer to related actions than strict duplicate litigation.

Lex specialis and gap filling

For GDPR proceedings within Article 81’s subject, Article 81 is the specific rule.

But Brussels I Recast may remain relevant to questions Article 81 does not fully answer, including:

• determining when a court is seized;
• recognition and enforcement;
• broader civil jurisdiction;
• related proceedings outside Article 81’s exact scope.

The two instruments should be interpreted coherently rather than assuming one completely abolishes the other.

24. Article 81 does not resolve the merits

A decision to contact, suspend or decline says nothing about whether the underlying processing is lawful.

Illustration

A German court suspends because a French court was first seized. This does not mean:

• the French claimant is correct;
• the German claim is weak;
• the controller complied with the GDPR;
• the first court’s future judgment will automatically bind every non-party. Article 81 concerns judicial administration and consistency, not substantive liability.

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25. Practical end-to-end illustration

A multinational employer operates one AI-based employee-monitoring system across France, Spain and Germany.

The system calculates productivity scores using:

• keystrokes;
• application use;
• location;
• communication metadata.

French proceedings

French employees sue first, alleging:

• excessive processing;
• invalid lawful basis;
• inadequate transparency;
• unlawful automated evaluation.

They seek an injunction.

German proceedings

A German employee later sues the same controller over the same tool, seeking:

• access;
• deletion;
• prohibition of scoring;
• compensation.

Step 1: Information

The controller informs the German court about the French action and provides the case reference.

Step 2: Mandatory contact

The German court contacts the French court and confirms:

• filing date;
• controller identity;
• system involved;
• legal issues;
• stage;
• remedies requested.

Step 3: Same subject matter assessment

The courts identify substantial overlap concerning the legality of the common monitoring system.

The German access claim may remain partly distinct.

Step 4: Suspension assessment

The German court asks:

• Is the French case near judgment?
• Would its judgment clarify the system’s lawfulness?
• Does the German claimant need urgent access?
• Can only the overlapping issues be stayed?
• Would suspension cause excessive delay?

The court might continue the access issue while suspending the broader lawfulness issue.

Step 5: Possible paragraph 3 application

The employer asks the German court to decline jurisdiction.

The German court must determine:

• whether both cases are still at first instance;
• whether the French court has jurisdiction over the German claim;
• whether French law permits consolidation;
• whether the German employee can participate effectively;
• whether limitation and cost problems arise.

If any mandatory condition fails, the German court cannot decline under paragraph 3.

This illustrates why suspension is much easier than consolidation.

26. Corrections to the supplied commentary

Several points require qualification.

First, Article 81 is not confined categorically to private-sector defendants. Public-authority cases may be geographically concentrated, but the text contains no blanket public-sector exclusion.

Second, Article 81 is best understood as potentially applying to both Article 78 and Article 79 proceedings. Recital 144’s reference to supervisory-authority decisions should not silently restrict the broader operative text.

Third, “same subject matter” is broader than identical claims but narrower than merely having the same defendant. The processing activity and risk of irreconcilable judgments are central.

Fourth, separate entities in the same corporate group are not automatically the same controller or processor.

Fifth, suspension is discretionary. Communication under paragraph 1 is mandatory once its threshold is met.

Sixth, suspension is temporary and should be reviewed. It must not cause indefinite denial of justice.

Seventh, paragraph 3 does not itself consolidate cases. It permits the later court to decline jurisdiction where the first court can hear and consolidate them under its own law.

Eighth, the assertion that simultaneous filing prevents either court from suspending is too rigid. Courts should determine the legally relevant time of seising and use cooperation and applicable procedural rules to resolve genuine uncertainty.

Ninth, Article 81 does not necessarily displace Brussels I Recast for every connected issue. It supplies a specific GDPR coordination rule, while Brussels I Recast may remain relevant for unresolved procedural questions.

Conclusion

Article 81 is the GDPR’s cross-border judicial traffic-control mechanism. It addresses the risk that courts in different Member States may rule independently on the same processing operation by the same controller or processor and produce outcomes that conflict legally or practically. Its structure is deliberately graduated:

• Paragraph 1 requires communication.
• Paragraph 2 permits suspension.
• Paragraph 3 permits the later court to decline jurisdiction only where strict conditions are met. The Article balances two important objectives. The first is consistency. Courts should avoid issuing contradictory decisions about a Europe-wide processing system. The second is effective judicial protection. Data subjects should not lose access to justice merely because another case involving different parties exists elsewhere. The first-seized court does not automatically acquire exclusive control over every connected GDPR dispute. The later court must consider:

• genuine overlap;
• identity of the controller or processor;
• nature of the processing;
• risk of irreconcilable judgments;
• urgency;
• progress of the first proceeding;
• interests of the parties;
• possibility of consolidation;
• right to a timely remedy.

The simplest summary is:

When connected GDPR cases arise in different Member States, the courts must first speak to each other. The later court may wait, and in narrower first-instance cases may step aside, but only where doing so promotes consistent justice without depriving a party of an effective remedy.