An airline passenger who sank their teeth into a fellow traveler turned out to be a pain for a plane load of people after the European Union’s top court said carriers aren’t responsible when rowdy customers force flights to be diverted.

The EU Court of Justice in Luxembourg ruled Thursday that such “unruly behavior” may be a so-called extraordinary circumstance exempting airlines from their obligation to compensate passengers whose journeys were disrupted.

On the first leg of a flight by Portuguese airline TAP SGPS SA from Brazil to Norway, with a layover in Lisbon, a passenger started biting a person on board and assaulting other passengers and flight crew who tried to calm the situation, forcing the plane to divert to another airport.

The plane arrived hours later than planned in Lisbon, causing people to miss their connections, but the airline refused to compensate them.

It’s not the first time the EU court has ruled in disputes over airline compensation. The tribunal ruled in previous cases involving the likes of Deutsche Lufthansa AG and EasyJet Plc that passengers who arrive “three hours or more after the scheduled arrival time” have a right to compensation, except in extraordinary circumstances.

While Thursday’s case predates the Covid-19 crisis, the pandemic may trigger even more litigation as customers only offered vouchers seek refunds for grounded flights.

The case is: C‑74/19, Transportes Aereos Portugueses SA