REGINA -- Saskatchewan's Court of Appeal is allowing all applicants to intervene in an upcoming court case involving the province and Ottawa over the national carbon tax.

A written judgment says all submissions from interveners must be limited to legal issues surrounding the tax.

The federal government had opposed a request by Alberta's United Conservative Party to be an intervener on the side of Saskatchewan.

Jason Kenney, the party's leader and a former federal cabinet minister, has tweeted he is pleased with the ruling and would be stepping up to fight for Albertans.

Saskatchewan has asked the court to rule on whether the federal government's plan to implement a carbon tax on the province is constitutional.

The case is to be heard in court in mid-February.