Vacuum Toilet Patent Dispute Decided by Federal Circuit

By Jonathan R. Tung, Esq. on March 29, 2016 | Last updated on March 21, 2019

A recent federal case brought both victory and defeat to two companies battling over patent disagreement related to vacuum toilets in commercial airplanes. The court addressed a number of pressing issues including the doctrine of assignor estoppel and whether or not a coin could reasonably be considered a "tool."

Assignor Estoppel

The case involves patent disputes over the design of vacuum toilets originally invented by a man who transferred his patent rights to his employer, which subsequently transferred again to the plaintiff. In the meantime, the defendant hired the inventor of this wonder toilet. In the view of the plaintiff, a number of the patents held by the defendant ran dangerously close to the patents that it had bought.

The legal doctrine operating in the background here is assignor estoppel, which is a doctrine that keeps an owner of a patent from suing a later assignee for patent infringement. An earlier court in Scientific Co. v Ambico. described this doctrine in this way: "Courts that have expressed the estoppel doctrine in terms of unfairness and injustice have reasoned that an assignor should not be permitted to sell something and later to assert that what was sold is worthless, all to the detriment of the assignee."

One of the primary issues before the district court (later affirmed by the Federal Circuit) was whether or not defendant-B/E could step into the shoes of the inventor and exercise inventor privileges -- namely to sue and cry "patent infringement" simply because it had hired him specifically for cure issues of privity. See also Shamrock Techs., Inc. v. Med. Sterilization, Inc. Although the court disagreed B/E's legal reasoning, on at least one issue, B/E/ came out on top.

Material Issue: Is a Coin a Tool?

Yes, you read that right. Another issue that eventually was found in favor if of MAG was whether or not "toollessly" was meant to refer only to conventional tools, or all useful tools of any kind. At the district level, MAG argued that the property doctrine of language construction demanded that the jury hear the issue of whether or not a coin was a tool. B/E's designs and MAG's designs at least appeared similar except that one required a conventional slot screwdriver for installation while another could be installed using a coin.

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