Montreal's much-hyped light rail system is facing a legal challenge from an environmental group that claims the province skirted the law and held inadequate public consultations on the project.

In a court filing Coalition Climat Montreal claimed the provincial government broke environmental laws by trying to fast-track the project.

The group said that the province's environmental review board (BAPE) refused to approve the project.

It also said initial consultations were insufficient and pointed out that no additional consultations were held after three additional train lines were announced.

"There's all kinds of incidents that weren't evaluated," said CCM attorney Ricardo Hrtschan.

He said the REM plan has many unanswered questions about its construction, station locations, and how many new riders it would attract.

"We're talking $10 billion for maybe 15,000 new users. It would be easier to buy them each a car with a chauffeur and paid vacations in Cuba for the whole family twice a year for the next 10 years," said Hrtschan.

Nobody has said how much tickets would cost on the privately-run train, or if users would be able to transfer to public transit without paying extra.

"There's basically no substance to the project," said Hrtschan.

The court filing states the project will have a massive and permanent effect on Montreal and the surrounding territory, yet the analysis of its impact has been minimal.

"This is the biggest project in the last 50 to 60 years and the people had seven days," said Hrtschan.

"All we want is that if the project is good, bring it in front of the citizens, bring it in front of the National Assembly."

The legal case continues in court Thursday.

Meanwhile other environmental groups are not worried about the expropriations and impact on farmland.

Steven Guilbeault of Equiterre said as far as he is concerned, any new train is a good train.

"We think it's a very good project for greater Montreal. It's the most important investment in transit since we built the metro," said Guilbeault.

The 67-kilometre light rail project known as the REM is expected to cost up to $6 billion with half of the funding coming from the Caisse de Depot, which will manage the rail line.

The Federal and provincial governments are providing most of the remaining funding, with Montreal paying

The rail line will link 27 stations running from downtown Montreal to the West Island and Trudeau Airport, will take over the existing Deux Montagnes train line, and will have a spur running over the new Champlain Bridge to the South Shore.

The Caisse is hoping to have the REM running in 2020.