Don't Be a "Patent Slacker"

Wealth of Ideas Newsletter, June 2004

In the world of patent infringement lawsuits, one defense often raised by the defendant is “laches.” Although it is frequently mentioned in conjunction with a similar defense, “estoppel,” and although the two are related, laches is not synonymous with estoppel. Laches, from the Old French, means slackness or negligence – a “sin of omission.” In intellectual property law, it is the unexcused failure of a patentee to take action in a timely manner against a patent infringer.

Why does it matter when the patentee brings suit against an alleged infringer? Because an excessive delay may put the defendant at a disadvantage: key witnesses may be no longer available or memories may have dimmed; important documents may be long gone. When laches is found, the patentee is barred from collecting damages accruing prior to the filing of the suit, but is still able to obtain an injunction barring the defendant from further infringement of the patents-in-suit.

Once the laches defense has been raised, the plaintiff may still offer evidence that the delay either was reasonable or not prejudicial to the defendant. Ultimately, the burden of proving laches rests with the defendant, who must prove that there was an unreasonable delay in bringing suit and that this delay prejudiced the defense. However, a rebuttable presumption of laches arises when the patentee waits more than six years from the time when he or she discovered (or reasonably should have discovered) the infringement to file a lawsuit.

The moral of the story: If you sit on your rights for too long, you may forfeit them.