Legal Definitions - intervening rights

Intervening rights is a legal principle in patent law that protects individuals or companies who, in good faith, began using or developing an invention *before* a patent related to that invention was reissued with broader claims.

Sometimes, a patent holder discovers an error in their original patent application that made the claims too narrow, meaning the patent didn't cover as much of their invention as it should have. They can then apply for a reissued patent with corrected, broader claims. However, if a third party started practicing the invention in a way that was *not* covered by the *original* narrow claims but *is* covered by the *new, broader* claims, intervening rights allow that third party to continue their activities without being accused of infringement by the reissued patent. This doctrine prevents retroactive punishment for actions that were legal and outside the patent's scope at the time they began.

• Example 1: Manufacturing a Component

  Imagine a company, "InnovateTech," holds a patent for a unique type of fastener, but their original patent claims mistakenly specified that the fastener must be made of "steel." A competitor, "RapidFasteners," then develops and begins manufacturing a very similar fastener made from "high-strength aluminum," which was not covered by InnovateTech's original "steel" claim. InnovateTech later realizes their mistake and successfully reissues their patent with broader claims covering fasteners made from "any durable metal alloy." Because RapidFasteners started manufacturing their aluminum fasteners before InnovateTech's patent was reissued with the broader claims, RapidFasteners can invoke intervening rights to continue producing and selling their aluminum fasteners without infringing on InnovateTech's newly broadened patent.

• Example 2: A Software Process

  Consider a patent held by "DataFlow Inc." for a method of processing large datasets, where the original patent claims specifically described the process as requiring "on-premises servers." A startup, "CloudCompute," then develops and implements a similar data processing method using "cloud-based servers," which was not covered by DataFlow Inc.'s original patent. DataFlow Inc. later identifies that their original claim was too restrictive and successfully reissues their patent with broader claims covering data processing methods using "any server infrastructure." Since CloudCompute began using their cloud-based server method before DataFlow Inc.'s patent was reissued with the broader claims, CloudCompute can assert intervening rights to continue operating their cloud-based data processing service without infringing on DataFlow Inc.'s reissued patent.

• Example 3: A Medical Device Application

  Suppose "HealthDevices Corp." has a patent for a medical diagnostic tool, but their original patent claims inadvertently limited its use to "detecting respiratory illnesses." "BioScan Labs," another company, then develops and markets a similar diagnostic tool for "detecting cardiovascular conditions," which was not covered by HealthDevices Corp.'s original "respiratory illnesses" claim. HealthDevices Corp. subsequently realizes the error and reissues their patent with broader claims covering the diagnostic tool's use for "detecting various internal medical conditions." Because BioScan Labs began developing and marketing their cardiovascular diagnostic tool before HealthDevices Corp.'s patent was reissued with the broader claims, BioScan Labs can exercise intervening rights to continue their activities without infringing on the reissued patent.