Plaintiffs in patent infringement lawsuits invariably seek a permanent injunction – a court order barring the defendant from future infringement of the patent or patents in suit. Until recently, such an injunction was granted automatically to a prevailing plaintiff. No question.

In 2006, the Supreme Court, in eBay Inc. v. Mercexchange, LLC, again overturned a substantial body of precedent (the decision, although surprising, is mercifully brief), deciding that the award of an injunction should be governed by the "traditional four-factor test applied by courts of equity." Under this test, the plaintiff must demonstrate (1) that it has suffered an irreparable injury; (2) that remedies available at law are inadequate to compensate for that injury; (3) that considering the balance of hardships between the plaintiff and defendant, a remedy in equity is warranted; and (4) that the public interest would not be disserved by a permanent injunction. Four questions.

Since eBay, however, the four-factor test has been distilled (not boiled – I drink bourbon, not tea) down to a single factor: competition between the plaintiff and the infringer. One question.

The lesson to be learned: if you don’t compete with the infringer, forget about a permanent injunction.