Unions are alarmed at the so-called sharing economy because it empowers individual workers, and so they’re leaning on politicians to rewrite the law to make it easier to organize drivers at ride-sharing services like Uber. The implications could extend across the entire U.S. economy.

In December under pressure from the Teamsters, Seattle enacted an ordinance that would allow taxi, limousine and other drivers who work as independent contractors to form unions. The goal is to create a new legal standard for unionizing independent contractors in industries stretching from ride-sharing to oil and gas and pharmaceuticals. The new law attacks a longstanding business model that has heretofore been exempt from union organizing.

Under the Sherman Antitrust Act, independent contractors are forbidden from coordinating the price and terms of a service. This makes collective bargaining illegal. Unlike employees, who may organize to negotiate terms with a company, independent contractors are different economic actors. Like many small business-folk, most Uber drivers are individuals who want to be their own bosses and establish their own relationships as contractors.

Under the Seattle ordinance, unionized drivers could be drafted into a system of price-fixing, creating anti-competitive effects for other drivers and less convenience for riders. A drivers’ union could theoretically set rules on the kinds of cars used by union members, hours driven, or even the number of drivers overall. Such anti-competitive practices create cartels and lead to higher prices, much like the taxi-medallion racket that still exists in cities in New York but that Uber has disrupted.

Seattle says its ordinance is kosher under the so-called state action doctrine, which allows immunity from antitrust laws if “the actions in question are an exercise of the state’s sovereign power.” But that argument doesn’t hold water when the action is by a municipality, and Washington state law has no provision to authorize independent contractors to engage in collective bargaining.