Taxi drivers in Washington caused a traffic jam Tuesday morning while protesting ride-sharing services that threaten their cabbie cartel.

Drivers with the D.C. Taxi Operators Association, an affiliate of the International Brotherhood of Teamsters, organized a caravan that traveled through downtown to Freedom Plaza. Once at the destination, they honked their horns and impeded traffic around the Capitol, to the consternation of Capitol Police.

Their protest was directed at Uber, a ride-sharing service that connects riders to drivers through a smartphone app. Uber advertises its services as "better than a cab," and many riders agree. While official D.C. taxis operate in a highly-regulated environment with a rigid fare structure, Uber operates outside of the box. Its fares are generally lower and its service generally better as a result.

According to the D.C. taxi operators' website, they oppose Uber because "this service is unregulated or, if there are regulations, they are minimal compared with taxi drivers. They play by different rules and it is hurting the taxi drivers' livelihoods." The drivers want the D.C. government to issue a cease-and-desist letter to the service.

Earlier this month, the state of Virginia issued a cease-and-desist to Uber and another ride-sharing company, Lyft, for operating without the proper permits. The D.C. government has been more hospitable to the popular startups, an inclination the cab association wants to change.

D.C. is the latest, but far from the only, site of protests over cab competition. Central London was gridlocked two weeks ago when cabbies protected by the Public Carriage Office organized a work slowdown. The London protest was a successful publicity stunt, although not in the way protestors had hoped: Uber's registrations increased 850 percent during the slowdown.