The federal government will table legislation Thursday that will clarify the rules around new supervised drug injection sites in Canada.

The rules come nearly two years after a Supreme Court ruling that allowed a Vancouver supervised injection site to remain open.

In the ruling, the court rebuked the Harper government for its efforts to shut down the Vancouver facility, but it said exemptions for supervised injection sites in the future must balance public health with public safety.

The rules are not very clear around how a supervised injection site — which supplies clean needles and offers drug users a safe environment to inject street drugs in an attempt to prevent overdoses and the spread of disease — can receive an exemption from federal drug laws.

The minister has the final say, but that decision is made behind closed doors.

The application process also makes use of the same form a veterinarian would fill out to use a prohibited substance to euthanize an animal.

After the court ruling in 2011, community groups in many other cities expressed an interest in opening safe injection sites, from Toronto and Montreal to Ottawa and Edmonton. But so far, no applications have been made, and Vancouver remains the only one in operation.

Sources in the government who have been working on this file say there will be a signficant number of criteria in the new legislation that will clarify where new sites can open up.

The new legislation will also give communities a formal voice in the process.

After the Supreme Court ruling, one of the drug addicts who launched the challenge said the Vancouver site is successful because it has the support of politicians at all levels of government, plus the local police and the community on the city's Lower East Side.