The concept of “class action” was not recognised under Thai law until 2015. The Civil Procedure Act of Thailand was amended by the Act Amending the Civil Procedure Code (No. 26) B.E. 2558 (2015) (the "Amendment Act"), which introduced class action proceedings for civil cases in Thailand under the Civil Procedure Code of Thailand (the "Civil Procedure Code"), Sections 222/1 to 222/49.

The Civil Procedure Code (as amended by the Amendment Act) allows a class of “numerous” persons to bring a class action in one set of proceedings in certain types of civil case, upon approval of the court. The Amendment Act was published in the Government Gazette on 8 April 2015 and became effective on 3 December 2015. Since then, class action proceedings have become the main form of collective actions in Thailand.

Class action proceedings under Thai law are representative proceedings – that is, claims are brought by a representative plaintiff on behalf of a larger group of persons.

There is no specific quantitative threshold on how many persons will be regarded as a “class” in order to qualify for class action proceedings. However, the representative plaintiff must prove to the satisfaction of the court that the class is “so numerous that to conduct a case as an ordinary case shall be complicated and impractical” and prove that to conduct the case as a class action is more just and efficient than as an ordinary case. Those persons must have the same rights, deriving from the same facts and legal principle, and have the same unique characteristics of the class, to form a class of persons under the Civil Procedure Code – that is, a group of individuals or juristic persons who have suffered from a common event.

The representative plaintiff must also meet certain criteria prescribed by the Civil Procedure Code, as follows:

1. the plaintiff must be a member of the class with the characteristics, interest and acquisition of the right to be a member of the class, as prescribed by the President of the Supreme Court (known as “typicality”); and
2. the plaintiff and its legal counsel must be able to conduct the case in such a way as to justly and sufficiently protect the right of the class of persons (“adequacy of representation”).

Class action proceedings in Thailand operate under an opt out regime. Every potential claimant who falls within the definition of the class of people is considered as a member of the class and will be entitled to compensation upon the court’s judgment, unless they opt out. Upon the court’s approval to proceed with the case by way of class action proceedings, the court will notify all known members of the class of the approval order and will publish such notice in a well-known daily newspaper for three consecutive days. The notice must include the prescribed period (which shall be at least 45 days) within which members of the class may register their wish to opt out of the class.

Members of the class who do not opt out of being a member will be prohibited from bringing a claim against the defendant in the same matter as the claim already commenced by the representative plaintiff.

Class action proceedings can only be brought in certain types of civil cases, prescribed by the Civil Procedure Code. These include tort claims, breach of contract cases and cases claiming legal rights under certain laws, such as laws relating to the environment, consumer protection, labour, securities and trade competition.

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The court has power to grant the usual remedies sought in civil proceedings such as damages, specific performance and injunctions.

Where the court imposes an injunction on the defendant, the court has discretion to determine the amount of costs that the defendant must pay to the plaintiff’s counsel as it deems appropriate, considering the difficulties of the case, and the length of time and work undertaken by counsel in relation to the action, including expenses.

If the judgment requires the defendant to pay damages, the court shall determine the costs payable to the counsel, which shall not exceed 30 percent of the amount of the compensation paid to the plaintiff and the members of the class.

There is no concept of pre-trial disclosure under Thai law.

In general, the parties are required to file their pleadings or statements to the court at the commencement of or during the proceedings.

In certain circumstances, the court may order the parties to grant the other parties access to their evidence, such as documents in their possession.

We are not aware of any governmental initiatives to introduce new collective actions or to change the scope and extent of existing class action proceedings under the Civil Procedure Code.