A Union engaged in a lawful primary strike is entitled to picket the Employer not only at its principal place of business but also wherever else the Employer carries on its business. The most common situation is the Employer who makes deliveries and pickups or otherwise performs work at a customer’s place of business. In these situations, the Union may lawfully follow the trucks and the drivers and picket the trucks and employees as they go about their business. This picketing is commonly referred to as “ambulatory,” “roving situs,” or “between the headlights” picketing.

The single most important thing to remember about ambulatory picketing is that it is directed only at the primary employer, not at the customer. It is illegal for the Union to try to involve the customer in its dispute with the primary Employer. In fact, the picketing may be enjoined and the Union may be liable for damages if it is found that the picketing was directed at the customer or at any company other than the struck Employer. The Union must therefore insure that the signs clearly identify the primary Employer, that picketing occurs only when the employees of the primary Employer are present, that the picketing be as close as reasonably possible to where the employees of the primary Employer are working, and that the pickets otherwise carefully follow their instructions.

These materials emphasize that pickets should not talk to anyone while they are picketing at a customer's premises, but should only give anyone asking about the picketing one of the Notices with which they will be provided and should otherwise direct all questions to the to the Union official in charge. This is a difficult restriction to enforce. Nevertheless, experience has shown that pickets all too often say the wrong things and that even completely proper and legitimate statements are misconstrued. The safest course is silence.