Dublin-based airline Ryanair has told a customer seeking flight delay compensation that it won't accept the jurisdiction of the British legal system, in a move that has raised questions over the future of how delay compensation is dealt with once a claim's been escalated to the courts.

The Ryanair customer, known only as Ms Menditta, is seeking compensation for a flight delay in 2015, and her case is due to be heard at Liverpool County Court in September 2017.

However, Ryanair has filed court papers arguing that when customers book they agree to clause 2.4 of its terms and conditions, which states that contract disputes will normally be subject to the jurisdiction of Irish courts.

The budget airline says the clause has existed for at least six years, but British customers have pursued claims through British courts during that time without it invoking the clause.

The issue of where passengers can bring compensation claims had previously been considered resolved, because in 2009 the European Court of Justice ruled such claims could be brought in the country that their flight departed from, the country where their flight landed, or the country where the airline is based. However the case of Ms Menditta appears to throw this into question.

Escalating a flight delay compensation claim to court is usually the last resort for a claimant. The first port of call would be lodging a claim with the relevant airline; if that's not dealt with satisfactorily you can contact the appropriate dispute resolution body (which in the case of Ryanair is the Retail Ombudsman). If all else fails you can can take your claim to court.

It's worth pointing out that Ryanair's stance in this case only has implications for the third and final stage of the compensation process (taking a claim to court).

Passengers are able to claim between £100 and £500 in compensation for delayed and cancelled flights, and many successfully do so each year. But if Ryanair's argument is successful, the costs and inconvenience of bringing a case in Ireland could deter its British customers from seeking compensation through the courts.

Hughes Walker Solicitors, representing Ms Menditta, said she was likely to challenge Ryanair's clause using the EU (formerly EEC's) 1993 Unfair Terms Directive, which it said "was created to protect consumers from companies who would take advantage of their customers".

Her legal costs are being funded through an arrangement with compensation firm FlightDelays.co.uk, which works with Hughes Walker Solicitors.

Ryanair objects to delay-claimants' use of 'claims chasers'

Ryanair has questioned Ms Menditta's decision to involve a third party, stating: "Ryanair requires our customers to submit flight disruption claims directly to Ryanair before engaging third party 'claims chasers'".

It added it insists on this to ensure customers get 100% of their compensation "without deduction of claims chaser fees", which it claimed could amount to up to 50% of the compensation payable.

FlightDelays.co.uk panel solicitor Nicholas Parkinson said Ryanair's clause "has come as a great shock to our clients who had absolutely no idea that Ryanair had put this clause in their terms and conditions".

He added: "The reality here is that, if passengers were only able to bring a claim using Irish solicitors in the Irish courts, the vast majority of passengers living outside of the Republic of Ireland will probably not bother to bring a claim at all – especially bearing in mind that most claims against Ryanair are only worth between £210 and £350.

"To our knowledge there are no other reputable airlines that have a similar clause in their terms and conditions (or, if there are, they do not attempt to rely on this clause)."

Check our Flight Delays guide to see if you're entitled to compensation for a delayed or cancelled flight.

Outcome of the case 'could affect all passengers' claiming delay compensation

Although its outcome has not yet been decided, the case has raised fears that passengers' flight compensation rights could be under threat.

Kevin Clarke of flight delay experts Bott and Co (which has no direct involvement in the case) said: "The argument [around this clause] is actually much bigger than Ryanair passengers and could potentially affect all passengers seeking to bring a claim for delayed-flight compensation.

"Should Ryanair win there would be nothing to stop them stipulating that claims be brought in any other court system – it doesn't have to be Ireland, it could be Israel or India or Indonesia.

"Passengers may very well have a valid claim, but should Ryanair refuse to pay them compensation they would then have to start proceedings in Israel, India or Indonesia and could find themselves fruitlessly searching for lawyers in those areas."

Clarke added that Bott and Co was forced to issue court proceedings against Ryanair in two out of every three such cases against the airline, to secure compensation for its clients.

Additional reporting by Megan French.