REGINA -- A lawyer for the Attorney General of Canada says the buildup of greenhouse gases in the atmosphere is a matter of national concern.
Sharlene Telles-Langdon says greenhouse gases cannot be distinguished from province to province once they are emitted into the air.
She says each province's emissions contribute to Canada's overall greenhouse gas levels.
Ottawa is laying out its arguments in a Regina court about why imposing a federal carbon price on Saskatchewan is constitutional.
The federal government says it can levy a carbon tax because climate change and greenhouse gas emissions affect everyone in Canada.
Lawyers for Saskatchewan and other carbon tax opponents say Ottawa is overreaching into provincial jurisdiction.
