Demers was first elected to the position in November 2013.
But his eligibility came into question when it was disclosed that he hadn’t lived in Laval for six months in the year leading up to the election.
Under Quebec law, a candidate for mayor must have lived in the municipality for at least 12 months prior to the election.
According to Judge Danielle Turcotte's ruling released today, Demers lived in Laval between 1971 and 1983, from 1999 to 2012, and moved back on Jan. 18, 2013, meaning he had far exceeded the required minimum.
Demers took over following a period of turmoil in the city.
Following Gilles Vaillancourt’s resignation in late 2012, the remaining members of his Parti PRO des Lavallois, which held every seat on the city’s council, voted to dissolve the party.
The province placed the city under third-party trusteeship in June 2013 after allegations emerged at the Charbonneau commission describing a culture of corruption in the former mayor's party.
Not long after, interim mayor Alexandre Duplessis resigned in the wake of a scandal allegedly involving prostitutes and extortion.