A Minnesota-based company can't thwart a rival's patent lawsuit even though the alleged infringing technology was installed on ships on the high seas, a judge in Minneapolis ruled Friday. While noting it was “not a clear cut or easy decision,” U.S. District Judge Ann Montgomery concluded that the Patent Act applies on U.S.-flagged ships in international waters, giving U.K.-based M-I Drilling Fluids UK Ltd. a chance to press its infringement claims.

St. Paul-based Dynamic Air Inc., which designs and manufactures pneumatic conveyance systems, asserted in January that M-I couldn't sue over alleged patent infringement that took place in the Atlantic Ocean thousands of miles away. The U.S. Patent Act doesn't extend into international waters, Dynamic's lawyers at Bassford Remele argued, and M-I's case hinged on 150-year-old case law that had been “effectively overruled.”

The judge disagreed. Montgomery, whose opinion addressed only the question of whether the Patent Act applies on U.S.-flagged ships in international waters, ruled that while U.S. patent laws don't afford protection to inventions outside the U.S., “this jurisdiction extends to the decks of American vessels on the high seas.”