Federal Circuit Affirms (Not) “Obvious to Try” Jury Instructions

Rentrop v. Spectranetics Corp. (Fed. Cir. 2008)

Dr. Rentrop is the chief of research at St. Vincent’s Hospital in NYC. For several years Rentrop used Spectranetics optical catheters to deliver LASER treatment. The Spectranetics catheters came in various tip diameters ranging from 1.4 mm to 2 mm. Finding those diameters too inflexible, Rentrop had the idea of using a 0.9 mm tip. Rentrop told Spectranetics of his idea and help them to create a prototype. Eventually Spectranetics obtained FDA approval and began marketing. In the meantime, the parties began to dispute over financial issues. Rentrop wanted a cut of the profits and so he filed for patent protection and eventually sued Spectranetics for infringement. The jury awarded $500,000 in damages.

On appeal, the Federal Circuit quickly affirmed. The most interesting legal issue of the case involves the pre-KSR jury instructions. The first part focused on the teaching-suggestion-motiviation test:

“In evaluating the scope and content of the prior art, you should keep in mind that there must have been some suggestion for a person skilled in the art to make the combination covered by the claims of the patent in issue in order for the claims to have been obvious. In other words, a claim in a patent is not obvious and invalid, simply because the claim combines elements that can all be found among the prior art references. It must have been a motivation or a suggestion to combine the limits in a manner disclosed by the patent.”

The Federal Circuit found this instruction proper – in context – because the instructions defined motivation as potentially arising “from common knowledge, or common sense of the person of ordinary skill in the art, without any specific hint or suggestion in a particular reference.”

Obvious to Try: The jury instruction on obviousness also included the statement that a “the test for obviousness is not whether or not it would have been obvious to try to make the invention.” The defendant argued that the instruction violates KSR. In KSR, the Supreme Court held that the Federal Circuit was in error to hold that a “patent claim cannot be proved obvious merely by showing that the combination of elements was obvious to try.” The Federal Circuit, however, was able to logically reconcile the two statements – noting that the jury instruction “does not imply that a showing that the specific combination of elements was obvious to try is insufficient to find obviousness.”


  • Northern District of California Chief Judge Vaughn Walker authored the opinion while sitting by designation on the Federal Circuit.
  • Spectranetics recently filed for ex parte reexamination of two of Rentrop’s patents. [LINK]