R. H. Drukker & Company, a nonunion general contractor, was engaged to construct a restaurant and adjacent office building on a large site in New Jersey. Drukker completed preliminary work on the Red Lobster Restaurant and had moved some of its excavating equipment to the office building site 500 feet away when pickets arrived from Local 825 of the Operating Engineers. The union established a picket line that covered entrances to both of Drukker's projects.

The union's signs claimed that Drukker's employees received less than union wages and endured substandard working conditions, but also stated that Local 825 had "no dispute with any other employer at this site." Although Drukker removed its employees and equipment from the Red Lobster job, the union continued to picket that area. Employees of neutral employers chose not to cross the picket line, halting progress on the Red Lobster job for two weeks.

The job superintendent of the Red Lobster site informed Local 825 that Drukker was no longer at that site, and the union withdrew to concentrate its efforts on the office project.

Before leaving, however, the union business agent warned that as soon as Drukker returned, so would the pickets. Work by other contractors immediately resumed on the restaurant. The NLRB ruled that the union had engaged in unlawful activity by picketing the Red Lobster site. Local 825 appealed this ruling to the circuit court.

What factors must the circuit court weigh to determine the legality of the union's conduct? Decide.