The federal government argued in two different courts in Quebec that the bar's request for a judgment on the constitutionality of the law was inadmissible.
Ottawa said the bar did not have sufficient standing to undertake the legal challenge but lost in both courts.
The Supreme Court announced Thursday it has refused to hear the case, paving the way for the bar to go ahead with its court challenge.
The bar says the law on mandatory minimum sentences does not contribute to helping protect citizens.
It also argues the legislation violates the independence of the judiciary and the basic principles of the legal system.
The Quebec bar refused to comment Thursday.