The US and UK both provide ways for people with similar legal claims to take collective action against large organisations. But while the underlying idea is the same, the way each system works is very different.
One key area of confusion is opt-out claims.
In the US, opt-out class actions are the norm. In the UK, they exist, but only in specific, tightly controlled circumstances.
This guide explains the differences between:
- US class actions
- UK group litigation (opt-in)
- UK opt-out collective proceedings
Why collective legal actions exist
Collective actions exist to solve a practical problem. If thousands — or even millions — of people are affected by the same wrongdoing, it makes little sense for each person to bring a separate claim.
Collective proceedings:
- Reduce pressure on the courts
- Make claims economically viable
- Strengthen claimants’ negotiating position
- Allow wrongdoing to be challenged that would otherwise go unaddressed.
Both the US and UK recognise this. Where they differ is how people become part of the case, and how much involvement is required from them.
Class action in the United States
What is a class action?
A class action is a lawsuit where one or more individuals, known as the lead plaintiffs, sue on behalf of a larger group of people with similar claims.
Once the court approves the case, everyone who falls within the defined class is included automatically — unless they actively opt out.
Certification process
One of the defining features of US class actions is the certification process.
Before the lawsuit can proceed as a class action, the court must certify the class, ensuring:
- The class is sufficiently large, making individual lawsuits impractical
- The claims of the lead plaintiffs are representative of the larger group
- There are common legal or factual issues shared by the class members
- The lead plaintiffs and their attorneys will adequately represent the interests of the entire class.
Role of the lead plaintiff
The lead plaintiff (or plaintiffs) plays a crucial role in US class actions. This individual or small group represents the entire class and takes part in decisions about the lawsuit, such as settlement negotiations.
Other class members are generally not required to participate actively in the proceedings, although they are still bound by the outcome unless they opt-out.
Compensation in class actions
In US class actions, compensation or damages are typically divided among all members of the class.
- The settlement or judgment amount is distributed based on the harm suffered by each claimant, but all share in the award.
- Often, compensation is automatically paid out to eligible class members.
Lead plaintiffs may sometimes receive a larger portion of the settlement as a thank you for their role in representing the class and managing the legal process. This is meant to acknowledge their added responsibilities and involvement compared to other class members. It’s also not unusual for them to have the worst injuries and the highest damages. How much extra compensation the lead plaintiffs get is down to the discretion of the court.
Group litigation in the UK (opt-in claims)
What is group litigation?
The most common form of collective action in the UK is group litigation, usually managed through a Group Litigation Order (GLO).
A GLO is a formal court order. It allows individual claims with common issues to be managed together, while each claimant keeps their own case.
How Group Litigation Orders work
Key aspects of a GLO include:
- Common issues: The claims involved in a GLO must have a shared issue. For example, all claimants must have been affected by the same data breach.
- Opt-in system: Claimants must opt-in to participate in the GLO by registering their individual claims with the court (their solicitors usually do this for them). This differs from US class actions, where claimants are automatically included unless they opt out.
- Case management: The court issues a formal order that provides a framework for managing the litigation, including procedures for evidence disclosure, trial schedules, and cost-sharing among the claimants.
Role of individual claimants
Unlike class actions, UK group litigation cases do not typically have a lead plaintiff. Instead, each claimant retains their individual status, meaning they must prove how they were affected. As such, participation is more active than in a US class action.
However, while there is no single representative, a few test cases may be selected to resolve common issues. The outcome of these test cases will apply to everyone within the group and help streamline the resolution of the litigation.
Compensation under a GLO
Claimants in UK group litigation may receive different awards depending on their individual circumstances and the strength of their cases.
Factors that might be considered when awarding compensation include:
- Individual circumstances: The extent of the harm or damage suffered by each claimant plays a major role in determining compensation.
- Strength of the case: Claimants with stronger evidence are more likely to receive higher compensation.
- Use of test cases: The outcome of these cases may set a precedent for other claims.
Claimants typically share the legal costs involved in group litigation, which can impact their final compensation. These costs may be deducted from the overall settlement amount before it is distributed.
Opt-out claims in the UK
Unlike the US, opt-out claims are not the default in the UK.
They are only available under a specific legal framework known as collective proceedings, and only for certain types of cases.
UK opt-out claims are currently limited to competition law breaches, such as:
- Price-fixing
- Abuse of dominance
- Anti-competitive behaviour
These cases are heard in the Competition Appeal Tribunal (CAT).
How opt-out collective proceedings work
If the CAT certifies a claim as opt-out:
- Eligible UK-based consumers are automatically included
- Individuals do not need to sign up or take action
- They can opt out if they choose
- Any compensation is usually distributed through a court-approved process.
Raising awareness of opt-out claims in the UK
Across the UK, some of the largest opt-out cases in history are moving through the courts.
Claims worth billions are being built, yet public awareness remains strikingly low. The result is billions in potential redress going unclaimed, year after year.
That’s the gap we want to close.
We’re not a law firm, and we don’t give legal advice. What we do is make complex collective actions understandable, explain what opt-in and opt-out claims actually mean, and help people find official claims they may be eligible for — safely and transparently.
Because collective actions only work if people hear about them in time.
As the UK’s consumer justice system continues to evolve, awareness may be the single most important factor in whether these landmark cases deliver real-world justice, or quietly pass most people by.
Which system is better for claimants?
All three systems have their benefits depending on the nature of the case and the preferences of the claimants involved.
Pros of US class actions:
- Efficiency: The opt-out system makes it easier to consolidate large groups of claimants.
- Starting a claim: It’s usually much easier to start a class action claim in the US than the UK.
- Less effort for claimants: Class members usually don’t need to participate once they are included in the case.
Pros of UK GLOs
- More control for claimants: Each claimant retains control over their individual case and can influence its outcome (to some extent).
- Individualised compensation: Claimants receive compensation based on their specific harm, which can lead to more tailored payouts.
- Straightforward settlement process: Unlike in the US, settlement does not require approval from the courts.
Pros of UK opt-out cliams
- Easier to get justice. Its much easier to join an opt-out claim as you are automatically included if eligible.
- Strong deterrent effect. Opt-out claims can involve millions of people. This creates a powerful incentive for businesses to comply with competition law.
- Less effort for claimants: Opt-out claimants usually don’t need to participate once they are included in the case.
In conclusion
Class actions have long been popular in the United States, tackling everything from consumer rights infringements to environmental damage.
However, corporate wrongdoing transcends geographical boundaries, and while the UK has historically been less litigious than the US, there is growing interest in collective redress on this side of the pond.
However, if you’re familiar with US-based courtroom dramas or media portrayals of class actions, be mindful they may give unrealistic expectations of the UK system! Understanding the nuances of UK group litigation will help you navigate the path to justice more effectively.
Join the Claim connects consumers with SRA-regulated lawyers. You can check your eligibility if a claim is open with one of our trusted legal partners. If a group action has not yet been launched, simply register your interest, and we’ll keep you informed if a partner firm decides to take a claim forward.
- Last Updated: January 2026
- Next Update Scheduled: January 2027
