The Supreme Court of Canada will be asked Tuesday to reopen a lopsided 1969 hydro deal that has so far generated $28 billion for Hydro-Quebec, versus about $2 billion for Newfoundland and Labrador.

Lawyer Doug Mitchell will argue for the province that the contract for the Churchill Falls hydro station in Labrador should be renegotiated to reflect vastly different circumstances.

He says negotiators almost 50 years ago could not have foreseen how energy markets have changed, allowing huge profits for Hydro-Quebec.

Good-faith principles at issue

At issue is whether partners in long-term contracts are obligated by so-called good faith principles to maintain fairness over time.

Hydro-Quebec says it helped finance Churchill Falls in exchange for price guarantees over the 65-year deal.

Natural Resources Minister Siobhan Coady says a win could mean billions of dollars as Newfoundland and Labrador faces deficits and mounting debt.