A lawyer for Saskatchewan says Ottawa's carbon-pricing law amounts to Big Brother forcing its will on the provinces.
He tells Ontario's top court that it's no coincidence the law only applies in four provinces with Conservative governments.
The court is hearing from interveners today on Day 3 of Ontario's constitutional challenge to the federal law.
Like Ontario, Saskatchewan calls the federal charge imposed in four provinces on fossil fuels an illegal tax.
Ottawa maintains the law is needed to fight greenhouse gas emissions in those provinces that aren't doing enough.
But Saskatchewan says the federal government is intruding on provincial authority simply because it doesn't like provincial policies.