Patent Litigation 101

A patent owner who finds that another party is making, using or selling its patented invention may bring suit for patent infringement. Federal courts have exclusive jurisdiction over patent infringement claims. Hence the litigation must be brought in a federal district court having jurisdiction over the parties. A party accused of infringement by letter or otherwise may bring a suit against a patent owner for declaratory judgment of patent invalidity or noninfringement. Either party in a patent infringement action may demand a jury, or the case can be tried to the judge if both parties waive their jury rights.

As a general rule, patent litigation presents unusually complex issues and a case will typically take at least 18 months or more to get to trial. During the initial discovery phase, each side will make demands on the other for responses to written questions and for the production of documents relevant to the issues in the case, followed by depositions of key witnesses, including the inventor, design and engineering personnel, and financial and accounting personnel. Next, in the expert witness phase, expert witness reports are exchanged, followed by depositions of the experts. Thereafter, either side may file a motion for summary judgment with supporting briefs and documentation, seeking a ruling from the court without the need for a full-scale trial. Following resolution of such motions, the case is ready for trial.

At some point in this process, it is necessary for the court to conduct a Markman hearing to determine proper construction of the claims. Even in a jury case, it is the job of the judge to determine the meaning of the claims as a matter of law. The terms in a claim are given their ordinary and accustomed meaning unless it appears the terms were used differently by the inventor. Claim language is construed by reference to the claims, the specification of the patent, the prosecution history of the patent and the prior art. Expert witness testimony is also often considered. The timing of the Markman hearing is currently a subject of considerable controversy. Some judges have even permitted the case to be tried to the jury before resolving disputes about claim construction. In other cases the Markman hearing has been held at a preliminary stage well before trial. In many cases, the judge's decision on the meaning of the claims may be determinative of the question of infringement.

The trial of liability issues generally divides into two areas: infringement and validity. The plaintiff-patentee has to prove infringement by a preponderance of the evidence. Plaintiff can do this by showing literal infringement - i.e., that the accused device embodies every element of the patent claim. Alternatively, plaintiff may also prove infringement under the doctrine of equivalents. This doctrine also requires that the accused device embody every element of the patent claims, but permits the patentee to show, with respect to an element that is not literally present, that that element is available by equivalents. To prove equivalents, the plaintiff typically attempts to show that the element performs substantially the same function in substantially the same way to achieve substantially the same result as the corresponding element in the claimed invention.

On the issue of validity, the patentee enjoys an advantage, since the patent is presumed valid and the defendant can only overcome that presumption of validity by clear and convincing evidence. The patent statute permits a variety of attacks to be made on patent validity. The most frequently seen attacks on patent validity are based upon obviousness, anticipation, prior disclosure or "on sale" status and best mode.

In addition to challenging validity, the defendant may also have available one or more equitable affirmative defenses, which, if proven, would constitute a bar to enforcement of the patent. In general these equitable defenses fall into three categories: fraud or inequitable conduct, laches or delay and estoppel, and patent misuse. [Read the Full Article]