By Randall Palmer

The case has the potential for widespread repercussions as unions seek a foothold in Wal-Mart stores in Canada and the United States.

It involves a store Wal-Mart opened in Jonquiere, Quebec, in 2001 and closed four years later after a union was certified to negotiate a collective agreement and the province of Quebec's labor ministry said the negotiations should go to arbitration.

"No employee at Jonquiere Wal-Mart should have lost their job because they were exercising their right (to union activity)," lawyer Claude Leblanc argued for the workers.

The Jonquiere store was the first in Canada or the United States to receive union certification, and Wal-Mart successfully argued in lower courts that it could not be forced to keep its stores open.

Without discussing the merits of unions, Wal-Mart argued that closing a store was "good and sufficient reason" to lay workers off.

But the workers' lawyers told the Supreme Court that this violated their freedom of association.

"We can't just stop at the bald assertion that the business closed," said another lawyer for the employees, Bernard Philion.

"We have to look deeper into it and see whether that was a real reason or was it just an excuse; was it just used to cover up the real reason, anti-union animus?"

In October, Wal-Mart closed the auto center at another store in Quebec after a collective agreement giving workers a 33 percent wage increase was imposed. It said the higher wages made the auto center unprofitable and that it would have to shut it down.

Unions have been certified at three other Canadian stores, in each case without a vote by employees, Wal-Mart says. No collective agreement has yet been reached.

Wal-Mart's lawyers were set to respond to the workers' arguments later in Wednesday's oral hearing. A judgment was not likely to be rendered for several months.