"The way that labor law is set up, longshore workers had to engage in illegal actions to have any chance of success. To allow an employer to refuse to use ILWU labor and undermine hard-won ILWU standards would threaten unionization on West Coast ports," says union organizer Joe Burns (a Working In These Times contributor and author of Reviving The Strike). "The problem is, labor law allows an employer to refuse to use union labor and then judges protect the employers with injunctions and threats against the union. Here, longshore workers decided to fight by labor's rules, not management's."
http://www.inthesetimes.com/working/entry/12045/longshoreman_struggle_poses_critical_question_about_breaking_the_law/