Injunctions for Patent Infringement: Historical Equity Practice Between 1790 - 1882

ABSTRACT:

A significant debate in patent law today concerns what remedy a patent owner may receive when a court finds a defendant liable for patent infringement. In eBay v. MercExchange (2006), the Supreme Court held that courts must use a “four-factor test historically employed by courts” in a “long tradition of equity practice.” This was the sole justification offered by the eBay Court for its four-factor test. Chief Justice John Roberts further claimed, from “the early 19th century, courts have granted injunctive relief upon a finding of infringement in the vast majority of patent cases.”

Both of these historical claims are conventional wisdom today in law and scholarship, and both claims are empirically unverified. This article tests both historical claims in reporting the results of a database of 899 opinions in which federal courts sat in equity in patent lawsuits. The database represents opinions by trial courts and appellate courts sitting in equity in all patent lawsuits filed between 1790 and 1880 compiled in the Federal Cases reporter.

The database confirms and challenges the conventional wisdom. First, eBay is wrong: there was no four-factor test in the “long tradition of equity practice” in patent cases. In the 899 opinions, no judge applied a four-factor test in granting an injunction, either for a permanent or a preliminary injunction. Second, Chief Justice Roberts is correct: courts did grant permanent injunctions in a vast majority of cases as a remedy for patent infringement. In the 899 opinions, courts awarded permanent injunctions in 91.2% of the cases in which a defendant infringed a valid patent. Given the stark absence of a four-factor test, the article describes the historical equitable doctrines applied by federal courts. Based on the opinions, it details how courts applied the same equitable doctrines and principles in patent cases as in redressing continuing trespasses of real property, protecting patents as much as they protected real estate and other property interests.