There's an effort to stall the project from the owners of the rival Ambassador Bridge, the aging structure that handles nearly one-third of all Canada-U.S. trade.
They're trying to persuade a judge to block the new government-supported bridge between Windsor and Detroit, which they say could put them out of business.
They want the Washington, D.C., District Court to grant an injunction that would prevent the U.S. Coast Guard from issuing a key permit for the project, which is supported by political authorities in both countries.
They say it would be unfair to grant the permit when they're being blocked in a parallel effort to expand their own private bridge.
Judge Rosemary Collyer has delivered some pointed barbs at the lawyers representing the Canadian and U.S. governments, and says she'll take her time with what she calls a complicated case.