A family from South Africa hopes to persuade a federal judge on Tuesday to let them stay in British Columbia, where they say they have found refuge from a potentially fatal disorder.

Three members of the Vivier family say they have porphyria, a rare allergy to sunlight.

Four years ago, they moved to Prince Rupert, on British Columbia's rainy north coast. They say they no longer have to hide from the sun, but they've been in a continual battle with immigration authorities.

Maggie Vivier enjoys the snow with her family

The only member of the family without the rare genetic disorder, Maggie Vivier, says the lives of her husband and children have been saved by moving under Prince Rupert's cloud cover.

"If any person could go back in time with me and spend one hectic day with us in South Africa, I would have done it in a wink," she said. "Maybe then they would realize this is not an exaggeration – this is a matter of life and death."

Lawyer Lorne Waldman argues on their behalf before a federal court justice in Toronto on Tuesday to allow the Viviers to stay on humanitarian grounds.

It's an argument they have lost twice before, in 2001 and 2002.

• FROM JAN. 28, 2002: South African family can't stay in Canada to avoid sun

Waldman says rejecting the plea was unreasonable.

Immigration officials turned down the family because they apparently thought their claims might have been exaggerated.

Should they lose this round, their only chance would be for the federal immigration minister to intervene directly on their behalf.