The Supreme Court appears willing to make it tougher to approve patents for computer software in a case that is being closely watched by technology companies.
But the justices on Monday struggled to come up with a middle ground that would recognize true inventions as opposed to those that simply take an old idea and blend it with computer wizardry.
The outcome of the case could send tremors through an industry that touches virtually every sector of the economy, from gadgets on smart phones to advances in anti-lock brakes.
The issue has divided the nation's technology giants. Companies like IBM say new restrictions could nullify thousands of existing patents. But firms including Google and Facebook say the free flow of software patents blocks other companies from innovation.