Corporate giant Wal-Mart finds itself in a showdown with a Quebec union before the Supreme Court of Canada.

The retail giant is defending its decision to shut down a Saguenay store in 2005 after employees agreed to form a union.

The store closure came just before an arbitrator was to impose a labour agreement for the 200 unionized employees.

The Supreme Court must decide whether Wal-Mart's move violated Canada's Charter of Rights and Freedoms which guarantees freedom of association.