Ontario's top court has ruled that a provincial law meant to protect farm workers is unconstitutional because it infringes on their labour rights.

In a decision released Monday, the Ontario Court of Appeal declared the Agricultural Employees Protection Act invalid.

The decision orders the government to provide agricultural workers with sufficient protections so they can exercise their right to bargain collectively.

The court has given the Ontario government 12 months to find a way to protect the right of agricultural workers to engage in collective bargaining.

The act, which came into force on June 17, 2003, excludes agricultural workers from the Labour Relations Act but provides some protections for organizing.

The decision is in response to a challenge from workers at Rol-Land Farms Ltd., a mushroom farm in Kingsville, Ont., where attempts at collective bargaining were ignored.