The anglophone merchants operate businesses in and around the Montreal area and were charged with violating the sign provisions of the law, better known as Bill 101.
The law requires the marked predominance of French on public signs, posters and packaging. It also applies to Internet postings.
One of the defendants' main arguments was that the French language is no longer threatened.
The companies also argued the sign law violated their freedom of expression as English-speaking citizens.
But in a 69-page ruling today, Quebec court Judge Salvatore Mascia dismissed the challenge, ruling the defendants did not show the situation of the French language had changed significantly.
All but one of the 24 businesses have been found guilty of violating Bill 101.
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