Opponents of allowing medically-assisted dying in Quebec are rallying their supporters to fight legislation on the issue that was re-introduced this week by the province's new Liberal government.

Two groups, Living With Dignity and the Physicians’ Alliance against Euthanasia, say they are planning a court challenge if -- and more likely when -- the proposed Act respecting end-of-life care becomes law in Quebec.

The law would allow some forms of medically assisted death in cases including "incurable serious illness," advanced states of "irreversible decline in capability," and "constant and unbearable physical or psychological pain 
which cannot be relieved in a manner the person deems tolerable."

Dr. Marc Beauchamp, a spokesman for the alliance, told CBC News that he got involved in the end-of-life care issue after losing a friend to suicide.

“Most of his friends were doctors. All of us could not detect depression, the distress that this friend was having,” he said.

He said it’s impossible to tell if someone is of sound mind when consenting to medical aid in dying, which is a central requirement of the proposed legislation.

Beauchamp says the safeguards against abuses of doctor-assisted death included in the legislation are not enough.

Legislation a priority for Liberals

Liberal Premier Philippe Couillard called the legislation a priority for his government during the recent provincial election.

On Thursday, his government made the unusual move of re-introducing legislation tabled by the previous Parti Québécois government that died on the National Assembly order paper when Quebec went to the polls in April.

It's re-introduction was supported by all parties in the National Assembly.

At the time of its introduction as Bill 52 in June 2013, PQ Social Services Minister Véronique Hivon said the legislation “is intended for people at the end of their life to die with autonomy and dignity."

The Liberals believe the proposed law has the support of most MNAs and Quebecers, but promised a free vote on the bill’s third and final reading in the National Assembly.

Court Challenge promised

Groups like Living With Dignity and the Physicians’ Alliance against Euthanasia are now mobilizing to sway MNAs to vote against the end-of-life care bill and, failing that, to mount a court challenge against it.

In a press release, they denounced the decision to hold a free vote only on the final reading and not on the motion to re-introduce the bill, saying it was “a parody of democracy.”

“It is vital that, in a true democracy, each MNA be granted the right to vote in accordance with his or her conscience, at all steps of the legislative process,” the press release stated.

The groups also said they would launch a court challenge on the constitutionality of provisions in the law that would decriminalize some forms of medically-assisted death.

“These provisions violate our Charters of rights and encroach on federal jurisdiction over criminal law, as euthanasia constitutes culpable homicide under our Criminal Code,” the press release said.

A spokesman for the federal justice minister told CBC News that it will be up to the courts to decide if Quebec is acting within the Constitution.