Conducting surveillance of workers participating in legal picketing can:

While surveillance might capture activities that could be interpreted as suspicious, legal picketing itself is a protected activity under labor law. Thus, surveillance is unlikely to yield valid evidence of criminal intent simply because the workers are exercising their legal rights.

This choice implies a restriction on who can conduct surveillance, which is not accurate. Surveillance can be carried out by various individuals or entities, not solely by trained security personnel. The legality and ethical implications of the surveillance are more pertinent than the qualifications of the individual conducting it.

Surveillance of picketing workers does not inherently serve as a valid defense in civil actions against a company. Instead, such surveillance may actually backfire, as it could be interpreted as an effort to undermine workers' rights, leading to further legal complications for the company.