The federal government has no legal duty to ensure First Nations have clean drinking water, even if Liberal ministers publicly suggest otherwise, Justice Canada lawyers say.

That's the defence the federal government is expected to mount in Ottawa this week in Federal Court, as it fights a national class-action lawsuit launched by a remote northern Manitoba First Nation in 2022.

Shamattawa First Nation, which has been under a boil water advisory since 2018, and its Chief Jordna Hill are pursuing the case for all First Nations members countrywide whose community was subject to a drinking water advisory in effect on or after June 20, 2020.

The plaintiffs argue First Nations have a basic human right to clean water that Canada has violated, describing the conditions facing their communities as "an urgent human rights crisis." In its statement of defence, Canada argues the government supports the delivery of potable water for First Nations as a discretionary political decision, calling it "a matter of good governance rather than legal duty."