Train companies are failing to properly inform passengers about their rights, a consumer group has claimed.
Operators are using industry-wide terms and conditions as a "smokescreen" to stop delayed travellers claiming compensation for expenses including missed flights, taxi fares and child-minding fees, according to Which?.
Under the Consumer Rights Act (CRA), which came into force on the railways on October 1 last year, passengers are entitled to claim for consequential losses when a service is not provided with "reasonable care and skill".
But Which? said the National Rail Conditions of Travel undermine passenger rights by unlawfully limiting liability for train firms.
The consumer group also found that 17 out of 24 operators are not providing enough information on passengers' rights on their websites.
Many include references to consumers' legal rights in relation to compensation but fail to make clear this includes rights enshrined in the CRA, it added.
Which? director of campaigns Vickie Sheriff said: "It's now six months since the Consumer Rights Act came into force in the rail industry but train companies are acting as if they are above the law and this is going unchallenged.
"Passengers have rights and must be aware of what they can claim for when they have a problem with their service. Train companies urgently need to address the misleading information they're providing on their websites and comply fully with the law."
A spokesman for the Rail Delivery Group, representing train operators, said: "Which? is wrong, train companies are not breaking any laws.
"Train companies' compensation arrangements already go beyond what is required under consumer law, and customers are getting an even better deal with new improved rights.
"Customers are clearly advised of their rights to money back. All train companies comply with the Consumer Rights Act and display the National Rail Conditions of Travel - which are approved by the Government - on their websites.
"Train companies will always consider reasonable claims for consequential loss where appropriate."
The latest bi-annual National Rail Passenger Survey by Transport Focus in autumn last year revealed that just 81% of passengers are satisfied with Britain's railways, a figure which has not been lower since spring 2007.
Punctuality has reached its lowest point in over a decade with more than one in 10 (12.3%) trains failing to reach their destinations on time last year.
This is the worst performance for a 12-month period since the year ending September 2006.
Rail fares increased by an average of 2.3% last month, sparking protests at stations.
A Department for Transport spokeswoman said: "We expect operators to make passengers aware of their rights to claim compensation and will continue to work with train operators to improve their schemes and provide clearer information on their websites?."