"A Member State may require its nationals to carry a valid identity card or passport when travelling to another Member State, irrespective of the means of transport used and the itinerary, subject to sanctions," the court said in a statement.
The verdict came after a Finnish citizen made a round trip between Finland and Estonia on boat in August 2015, during which, he crossed the international waters between the two countries without having his valid passport with him. While passing through a border check in Helsinki on his return, he was charged with a minor border offence — crossing the Finnish border without a travel document. Although he had his driving license, the document was not sufficient.
Under the Finnish law, the person was subject to a fine of up to 20% of the offender's net monthly income, which, in this case amounts to 95,250 euros ($109,966). The Supreme Court of Finland decided to consult the EU court on whether this rule is compatible with the right of citizens of the Union to freedom of movement.
"In that regard, the Court observes that, while it is open to Member States to impose a fine in order to penalise a breach of a formal requirement relating to the exercise of a right conferred by Union law, that fine must be proportionate to the seriousness of the offence," the statement read.
Regarding the case of the Finnish citizen, the court added that the fine imposed on him for such a minor offence was not proportionate to its seriousness.