SAN FRANCISCO — A pair of district court rulings handed down Friday on the scope of U.S. antitrust law reinforce plaintiffs lawyers’ ability to sue foreign companies over claims that they fixed prices, even when the transactions at issue took place overseas.

The decisions by U.S. District Judges James Donato and Jon Tigar of the Northern District of California in separate cartel cases both affirm that foreign companies are liable under U.S. law when the goods at issue are shipped to the U.S. The judges rejected arguments that foreign companies could avoid the grip of U.S. antitrust law by billing sales to a middle man before selling the goods into U.S. commerce.