European Union’s top court ruled on Tuesday that its member states cannot imprison foreigners simply because they illegally entered the country.
The ruling was given in a case involving a Ghanaian woman who was apprehended in France.
The EU has been grappling with an influx of migrants and asylum seekers since 2015.
Many member states are now seeking to crack down on economic migrants, who have no right to stay, in order to better manage those deserving international protection.
The case before the European Court of Justice predates last year’s migration surge, but could have a bearing on decisions taken in response to the high number of arrivals.
In March 2013, Selina Affum, from Ghana was stopped by French police at the Channel Tunnel crossing to Britain on board a coach travelling from the Belgian city of Ghent to London.
Affum presented a passport bearing another person’s name and photo. She was placed into custody for illegally entering France.
Affum challenged her treatment, and a French court turned to the ECJ for advice on the legality of her imprisonment.
The Luxembourg judges ruled that taking into custody a non-EU national only for illegal entry violates the bloc’s rules and undermines their effectiveness, since this delays procedure to send the person back to their country of origin or a country of transit.
The court said that EU rules only allow imprisonment if foreigners stay on despite being the subject of a return procedure or if the risk of the process is being compromised.
“If the person breaches a ban on re-entering the member state; or if they commit other crimes,” the court said.