Employees cannot lawfully strike unless a strike vote by secret ballot is taken within 30 days or less before the collective agreement expires or at any time after the collective agreement expires and more than 50 per cent of those voting by secret ballot in favour of the strike. A strike vote must be by secret ballot and all people eligible to vote must have ample opportunity to do so. All employees in a bargaining unit, whether or not they are members of the union, are entitled to participate in such a vote.