To build a deadlier mousetrap: Where high-tech meets low-tech

The latest case concerning the scope of microprocessors is found, not in the world of computers, but in this battle over the right to electrocute pests.

Chris Ryan is an intellectual property lawyer at the law firm of Vinson & Elkins, LLP. His practice is chiefly focused on patent litigation where Chris represents both plaintiffs and defendants, but Chris has also advised clients in matters of patent, copyright, and trade secret licensing. Prior to practicing law, Chris worked as a business strategy consultant with McKinsey & Co., advising clients on matters of business and technology strategy, organization, and operations. Click here for Chris' official law firm bio. The postings on this site were created for informational purposes only and do not constitute legal advice. Disclaimer.
3 min read

If you thought that the issue of whether a patent covered the use of a microprocessor could only concern the computer or semiconductor industry, think again. High tech has extended its reach to zapping rats (literally).

Build a better mousetrap, and the world will beat a path to your door. Such were the aspirations of Bob Noe, the founder of Agrizap--maker of the patented Rat Zapper, a trap for dispatching pests through electrocution. Agrizap's Rat Zapper, which is about the size of a shoebox, is powered by four AA batteries, and is sold online for about $40 at RatZapper.com.

The slightly larger Rat Zapper Ultra uses D-cell batteries which, according to the Website, enables it to kill "even bigger, badder rats and mice." In the event of serious infestation, or for those with an overdeveloped desire to integrate their equipment, Agrizap also offers the ultimate high-tech equipment including its Battle Station command post and radio-monitoring equipment for use with its traps.

For several years, under an oral marketing agreement, Noe sold the Rat Zapper through Woodstream, one of the nation's oldest mousetrap makers. The relationship broke down in 2003 when Woodstream launched its own competing Electric Mouse Trap, a CPU-controlled rodent-killing device, for which it now appears to hold several of its own patents. In July 2004, Agrizap sued Woodstream for patent infringement and fraudulent misrepresentation in the Eastern District of Pennsylvania's Philadelphia division.

The lawsuit raised so many issues that it would make a good case study for students of intellectual property law. There was even a discovery dispute of some note, when Agrizap's former operations manager testified during his deposition that the older Gopher Zapper product had been offered for sale at a California trade show. Three months later, the witness tried to recant his testimony through written changes to the transcript. The court did not allow the changes, and the Gopher Zapper was considered "prior-art" to the patent-in-suit.

The claims of Agrizap's patent-in-suit are directed to a rodent trap with a mechanical portion, in which the rat would physically be made part of a high-voltage electric circuit, and an electrical portion, which used discrete electrical components including a "resistive switch" to sense the presence of the rodent and administer the lethal electric dose. The patent also required a "timing module" to switch off power and disarm the device.

Woodstream challenged nearly everything about Agrizap's patent claims, arguing first that it did not infringe and that the claimed invention was previously known, obvious, barred by prior sale, not enabled, indefinite, listed the wrong inventors, and was unenforceable. Ultimately, after a two-week trial, the jury was not persuaded by these defenses and found that Woodstream had infringed claim 16 of the patent. That means the jury found that Woodstream's microprocessor was the same as the discrete resistive switch and discrete timing module claimed in patent.

The law that allows computer software to be patented is rooted in the notion that software instructions transform a general purpose CPU into a different machine by creating electrical paths within the device. Extending this reasoning, some patent holders have tried to argue that a CPU, when programmed to perform a given function, is literally transformed into the specific set of discrete electrical components found in their patent claims. This approach has not found favor with the courts. For example, in the Overhead Door case, the Federal Circuit held that a software instruction running on a microprocessor could not literally infringe a mechanical circuit component. Following the Overhead Door decision, the judge ruled that as a matter of law, Woodstream's microprocessor-based device could not literally infringe the patent whose claims were directed to discrete circuit components.

Agrizap did not leave the courtroom empty-handed. The jury found Woodstream liable for fraudulent misrepresentation and awarded $1.28 million in damages. In this instance, the judge did not disturb the jury's decision because evidence presented at trial showed that in response to specific requests for assurances that it was not copying the Rat Zapper, Woodstream's senior management misled Noe. The company was, in fact, planning to develop and market its own competing product.

Both sides have appealed the decision at the Federal Circuit, where a hearing on the issue took place Feburary 7. Stay tuned for the latest chapter in the war of the rats--and the Federal Circuit's latest decision concerning microprocessors.