The opt-in and opt-out options under the WAMCA

What is meant by the opt-in and opt-out options?

Proceedings under the Settling of Large-scale Losses or Damage (Class Actions) Act (the "WAMCA proceedings") are, in principle, automatically binding on all injured parties who belong to the group determined by the court and who have a place of residence or stay in the Netherlands. Injured parties who do not wish to be bound by the collective action may submit a so-called "opt-out declaration".

For injured parties who belong to the group determined by the court but do not have their place of residence or stay in the Netherlands, the opposite applies: they are not automatically bound by the collective action⁽¹⁾.  These injured parties may submit an “opt-in declaration” in order to be bound by the outcome of the proceedings. 

The nature of the claim may mean that the opt-in or opt-out option is not meaningful. A court may rule that individuals do not need to submit an opt-in or opt-out declaration to be bound by the judgment. In such a case, everyone belonging to the designated group is bound.⁽²⁾  

The first opt-out option for injured parties residing in the Netherlands

Once an exclusive representative has been appointed and the court has determined the narrowly defined group of persons whose interests are being represented, the court sets a time limit within which injured parties with their place of residence or stay in the Netherlands may submit an opt-out declaration to the court registry. If an injured party does not submit an opt-out declaration within this period, they are bound by the collective action and its outcome.

This binding effect takes effect as soon as the collective action commences. From that moment on, an injured party may no longer initiate their own proceedings. Furthermore, it is not possible to submit an opt-out declaration before the deadline set by the court. If an injured party already has their own proceedings pending, they must wait until an opt-out period has been set in the WAMCA proceedings. They will have to suspend their proceedings until they have been given the opportunity to submit an opt-out declaration.⁽³⁾

If a significant number of injured parties decide to make use of the opt-out option, this may have consequences for the progress of the proceedings. In such a case, the court may rule, pursuant to Article 1018f(1) of the Dutch Code of Civil Procedure ("DCCP"), that it is no longer justified to continue the collective action. An example of this is the collective action initiated by FNV and CNV against Temper. In this case, the Amsterdam District Court found that almost a quarter of Temper’s workers had submitted an opt-out declaration. The court ruled that this number was too large to continue the proceedings. This led to the collective action, insofar as it related to the claims on behalf of Temper’s workers, being terminated.⁽⁴⁾ 

The opt-in option for injured parties outside the Netherlands

Pursuant to Article 1018f(5) DCCP, an opt-in regime applies in principle to injured parties without a place of residence or stay in the Netherlands, meaning that they must expressly consent to the representation of their interests in order to be bound by the outcome of the proceedings. The court determines how these foreign injured parties are to be informed, unless an international or EU binding regulation prescribes a method of notification. Where necessary, injured parties are provided with information in a language other than in Dutch.⁽⁵⁾

At the request of a party to the proceedings, the court may rule that the opt-out regime under Article 1018f(1) DCCP also applies to this group of injured parties.⁽⁶⁾ This was requested by the trade unions FNV and CNV in the collective action against XPO Supply Chain Netherlands III B.V., in which the central issue was which pension scheme the employees concerned would participate in.⁽⁷⁾ XPO Supply Chain Netherlands III B.V. allegedly did not have the address details of affected parties without a place of residence or stay in the Netherlands, meaning that these individuals could not be bound by the outcome of the collective action. However, the court considered, drawing on the legislative history, that such a request can only be granted if the court determines that an opt-out regime for foreign persons is also in the interests of the party that did not request it. This may, for example, be the case with a view to achieving genuine and comprehensive finality.⁽⁸⁾  

In this judgment, the court rejected the request by FNV and CNV. Given the nature of the claim, which concerned the far-reaching question of which pension scheme the employees in question participate in and which indirectly also involves pension insurers, applying an opt-out regime to a group of persons of unknown size would have undesirable consequences. A group of persons unknown to the parties would then be bound by the outcome of the judgment without their knowledge.⁽⁹⁾ 

An example of a ruling in which the court did grant the request for the application of the opt-out regime is the collective action brought by Stichting BREIN. This foundation brings collective actions on behalf of its members and affiliated parties in the context of intellectual property fraud.⁽¹⁰⁾ The members provide financial support to Stichting BREIN. During the proceedings, Stichting BREIN argued that a very large number of members were based abroad and that these parties were not prepared to submit an opt-in declaration for all individual WAMCA proceedings. An opt-in regime would therefore mean that Stichting BREIN could no longer represent the interests of these foreign parties, even though they were paying for this service and had never objected to the proceedings brought by Stichting BREIN.⁽¹¹⁾ The court found this sufficient to grant Stichting BREIN’s request. ⁽¹²⁾

Provision of information to the injured parties regarding the opt-in and opt-out options 

The court determines how injured parties are to be informed about the option to opt out of the collective claim or, conversely, to consent to participation. The exclusive representative is responsible for providing this information, unless the court decides otherwise.
To ensure that injured parties are properly informed about the opt-in and opt-out options, the law stipulates the manner and content of the information that injured parties must, in principle, be provided with:⁽¹³⁾

• by ordinary letter, the known persons whose interests are being represented shall be notified as soon as possible of (i) the appointment of the exclusive representative, (ii) the collective claim, and (iii) the precisely defined group of persons whose interests are being represented by the exclusive representative in this collective claim; and
• a collective claim must also be announced as soon as possible in one or more newspapers to be designated by the court.

The period set by the court within which persons may submit a declaration shall be at least one month following the public announcement. In practice, a period of two to three months is often applied, sometimes at the request of the parties, calculated from a specific point in time following the interim judgment. ⁽¹⁴⁾

The court may impose additional information requirements or prescribe a different method of providing information. The court may also give the parties the opportunity to comment on rules relating to the opt-out and opt-in. ⁽¹⁵⁾

The ruling by the Midden-Nederland District Court, in which a foundation was appointed as the exclusive representative for all women in the Netherlands who had had Essure ⁽¹⁶⁾ implanted, illustrates the instructions the court may issue regarding how and on what matters an exclusive representative must inform the injured parties. The parties have also agreed on the following instruction, which the judge deemed sufficient to inform the women in the narrowly defined group ⁽¹⁷⁾: 

• the foundation will send a letter containing the announcement by post and by email to all women who have registered with it and for whom the foundation has contact details;
• the foundation will place an advertisement in the Volkskrant of at least a quarter of a page announcing the collective action; and
• the foundation will publish the interim judgment of 9 January 2025 on its website regarding the collective action against Bayer (https://stichtingessureclaims.com/nl/).

The court considered this sufficient to inform the women. An earlier interim judgment had also already been published in the Central Register for Collective Claims, and the interim judgment was available for inspection at the court registry. ⁽¹⁸⁾  The foundation was required to send the announcement to the women known to it as soon as possible, but no later than two weeks after the interim judgment, and it had to place the advertisement containing the announcement in the Volkskrant within two weeks.⁽¹⁹⁾The court also drew up a text for the notice.⁽²⁰⁾ The women from the narrowly defined group were given two months to inform the court if they did not wish to be bound by the proceedings.(21) 

In some cases, a judge does not apply the regulations in view of the idealistic nature of the claims.(22) This was the case in the collective action brought by Environmental Federations and the Healthy Water Foundation against the State. The District Court of The Hague ruled that the provisions did not need to be applied, because in the event of a judgment in favour of or against the claim, everyone concerned would be bound by the legal consequences. This concerned a collective action to protect the public interest.⁽²³⁾ 

The second opt-out option

In addition to the opt-out option discussed earlier, the WAMCA provides for an additional opt-out option. Once a judgment has become final, it is binding on the parties to the proceedings and the injured parties.  However, Article 1018k DCCP offers protection to injured parties whose loss only became known after the first opt-out option had expired. A person who could not have been aware of their loss at the time of the opt-out or opt-in option is not bound by the agreed collective settlement of claims if they notify this in writing after their loss has become known.

Nor would it be reasonable to render a court judgment binding on a person who, at the time of the proceedings, could not have been aware that it also applied to them, because they had not yet suffered any loss at that time. This person has the option, once their loss has come to light, to opt out of being bound by the judgment pursuant to Article 1018k(2) DCCP. 

The notification of not wishing to be bound must be addressed to the defendant or to the person referred to in Article 7:907(2), preamble and under g, of the Dutch Civil Code. This is usually a legal entity responsible for paying out the compensation on the basis of the established collective settlement, also known as the claim administrator.  The defendant is authorised to set a period of at least six months for the person concerned to indicate that they do not wish to be bound by the judgment.

Conclusion 

In short, the WAMCA is, in principle, automatically binding on all injured parties who belong to the group determined by the court and who have a place of residence or stay in the Netherlands. For injured parties residing abroad, an opt-in regime applies in principle, although the court may deviate from this in exceptional circumstances. Once the parties have had the opportunity to make use of the first opt-out option, the settlement phase begins. More on this in our next Insight.

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[1] Article 1018f(5) of the Code of Civil Procedure. 
[2] District Court of Amsterdam, 18 June 2025, ECLI:NL:RBAMS:2025:4192, paras. 2.19–2.20. 
[3] M. Goorts & T. Mimpen, Procesrechtelijke aspecten van de Wet afwikkeling massaschade in collectieve actie (WAMCA), Zutphen: Uitgeverij Paris 2024, p. 72.
[4] District Court of Amsterdam, 11 October 2023, ECLI:NL:RBAMS:2023:6389, paras. 2.15–2.17.
[5] Article 1018f(3) of the Code of Civil Procedure.
[6] Article 1018f(5) of the Code of Civil Procedure.
[7] District Court of Oost-Brabant, 14 September 2022, ECLI:NL:RBOBR:2022:3931, para. 2.13.
[8] District Court of Oost-Brabant, 14 September 2022, ECLI:NL:RBOBR:2022:3931, para. 2.15.1.
[9] District Court of East Brabant, 14 September 2022, ECLI:NL:RBOBR:2022:3931, para. 2.15.2.
[10] District Court of The Hague, 3 May 2023, ECLI:NL:RBDHA:2023:6324.
[11] District Court of The Hague, 3 May 2023, ECLI:NL:RBDHA:2023:6324, para. 2.3.
[12] District Court of The Hague, 3 May 2023, ECLI:NL:RBDHA:2023:6324, para. 2.4.
[13] Article 1018f(3) of the Code of Civil Procedure.
[14] Van Mierlo, in: T&C Rv, commentaar op art. 1018f Rv. See, for example, District Court of Amsterdam, 29 January 2024, ECLI:NL:RBAMS:2024:412, para. 2.6.
[15] District Court of Amsterdam 29 January 2024, ECLI:NL:RBAMS:2024:412, para. 2.1.
[16] Essure was a permanent sterilisation method that caused serious health problems in thousands of women.
[17] District Court of Midden-Nederland, 26 March 2025, ECLI:NL:RBMNE:2025:1209, para. 2.6.
[18] District Court of Midden-Nederland, 26 March 2025, ECLI:NL:RBMNE:2025:1209, para. 2.7.
[19] District Court of Midden-Nederland, 26 March 2025, ECLI:NL:RBMNE:2025:1209, para. 2.8.
[20] District Court of Midden-Nederland, 26 March 2025, ECLI:NL:RBMNE:2025:1209, para. 2.10.
[21] District Court of Midden-Nederland, 26 March 2025, ECLI:NL:RBMNE:2025:1209, para. 2.6.
[22] District Court of The Hague, 25 September 2024, ECLI:NL:RBDHA:2024:14834, para. 3.23.
[23] District Court of The Hague, 28 May 2025, ECLI:NL:RBDHA:2025:9162, para. 3.8.