When  an employer modifies its employment policy to require employees to arbitrate their disputes and clearly communicates to employees that continued employment will constitute assent to an arbitration agreement, the employees will generally be bound by the agreement if they continue to work for the employer.  However, that is not true if, as in this case, an employee promptly rejects the arbitration agreement, refuses to be bound by it, and challenges the employer to fire him if it objects.  In those circumstances, the employee is not bound by the arbitration agreement even though he continued working for the employer after the new policy became effective.