How have courts interpreted a reservation of rights clause?

Because of this the courts have said: It is a basic principle of contractual interpretation that a provision that is ambiguous or capable of more than one reasonable interpretation shall be interpreted against its drafter. Given the context of unequal bargaining power between employees and employers, the policy reasons under scoring this principle are magnified. For this reason, courts have interpreted reservation of rights clauses restrictively against employers, finding that they must be explicit about affecting the benefits of retired employees (cannot simply refer to the benefits of current employees) and that they must also be explicit in conveying a right to introduce changes after the point of retirement. O’Neill v. General Motors of Canada, 2013 ONSC, 4654, at para. 71 Analysis