Weeks after West Coast shippers and dockworkers resolved a tense and costly contract dispute, labor strife is returning to California ports. Backed by the International Brotherhood of Teamsters union, hundreds of truck drivers went on strike indefinitely Monday at companies that service the the ports of Los Angeles and Long Beach, the nation’s busiest cargo hub. Together, the four targeted companies -- Pacific 9 Transportation, Intermodal Bridge Transport, Pacer Cartage and Pacer subsidiary Harbor Rail Transit -- employ about 500 drivers, according to Teamsters official Barb Maynard.

Workers say they’re subject to illegal retaliation after asking to be treated as employees rather than independent contractors -- the latest salvo from Los Angeles and Long Beach port truck drivers in their ongoing battle with short-haul trucking companies. Since the summer of 2013, the Teamsters have organized walkouts at several different trucking outfits, pressuring them to classify their workers as employees. Workers last went on strike this past November.

Misclassification runs rampant in the industry, labor advocates say. About 50,000 of the nation’s 75,200 port drivers are misclassified, including 16,400 of the 25,000 drivers in California, according to a recent report commissioned by Teamsters supporters. Independent contractors lack rights to minimum wage and overtime pay and cannot join unions; nor are they entitled to workers' compensation or unemployment insurance. They’re also required to eat a large chunk of business costs, as trucking companies regularly deduct money out of paychecks for fuel and maintenance. 

Compared with the high-stakes dockworkers’ dispute earlier this year, the economic impact of Monday’s trucker strike, like previous such work stoppages, is minimal: “It’s not impacting the flow of cargo at this point,” Phillip Sanfield, spokesman for the Port of Los Angeles, said Monday morning. That could change later in the day, cautioned Sanfield, especially if dockers from the International Longshore and Warehouse Union refuse to handle cargo from companies targeted by strikers. The ILWU, however, has not successfully honored such picket lines in the past. Port of Long Beach spokesman Lee Peterson echoed Sanfield, noting traffic was moving regularly this morning but adding that “we might see some delays.”

As the union seeks to organize truckers, it has mounted legal challenges, with some success. Last year, the National Labor Relations Board ruled workers for Shippers Transport Express were misclassified. Earlier this year, the company reclassified its 111 drivers as employees and recognized the Teamsters union. The Teamsters are in talks with other companies, encouraging them to follow suit.   

The median annual wage for truck drivers is $39,520, according to the Bureau of Labor Statistics. Independent contractors, according to the union-commissioned study, make just under $29,000 before taxes.