The US Supreme Court will decide if ConAgra Foods violated antitrust laws in a patent dispute.

After receiving a patent for a meat-browning process in 1999, ConAgra warned other food companies in writing not to deal with anyone selling a similar process.

Unitherm Food Systems had its own process patented six years earlier, and sued in federal court, which awarded it more than US$19m and ruled that ConAgra was fraudulent in its patent application and tried to monopolise the market with its warnings.

It also stated ConAgra should never have received a patent which was substantially similar to Unitherm's. ConAgra appealed, arguing that it thought it had a valid patent, and the Supreme Court will most likely decide based upon procedural issues of the lower courts, rather than the merits of the case.