BRUSSELS—The European Union's top court has said that morbid obesity could qualify as a disability if impacts on a person's ability to work, in an opinion that could have far-reaching implications for employers in Europe.

The European Court of Justice was asked to assess whether being obese could qualify as a disability under EU employment rules, after a Danish childminder claimed he was dismissed unfairly because of his weight.

Karsten Kaltoft had been working for 15 years looking after children in his own home in Billund, Denmark, when his contract was ended in 2010. Mr. Kaltoft claimed that the municipal authorities for which he worked dismissed him because of his weight, a charge denied by his employers. Throughout his employment Mr. Kaltoft never weighed less than 160 kilograms, and he was classified as obese.

His complaint has attracted plenty of media attention and is seen by some as a test case for the treatment of obese employees in the EU.

"It is the first time ever that a case has been brought at EU level regarding protection due to clinical obesity. This fact alone renders the case of general public importance," said Jacob Sand, attorney and partner at the Danish law firm Gorrissen Federspiel.