His normal entry method blocked, Santa may have to resort to alternate means. Above, a Guatemalan firefighter rappels down the Belize bridge to deliver gifts to homeless children.Josue Decavele/Reuters

Humans solve intractable problems with incredible technology.

When faced with a river, we build a dam. When faced with rotting meat, we build a refrigerator. When faced with long distances, we build a continent-spanning Interstate Highway System.

And when faced with a plump man invading our homes bearing unwanted junk manufactured by a brainwashed labor force, we invent the Santa Claus Detector.

Patented in 1994, the Santa Claus detector went straight to the root of the issue: the jolly old elf’s entrance via chimney. It proposed hanging a trip wire—or, rather, a trip-ribbon—across the open hearth, attached to a switch in a stocking. When the ribbon was pulled, the light turned on and, voilà, Santa detected.

Real illustrations from a real U.S. patent (Patent US5523741 A)

Truthfully, the patent concerned itself less with catching the felonious Father Christmas than alerting children to his arrival. “According to modern folklore, if a child has behaved during the previous year, Santa Claus will reward the child by placing one or more Christmas presents under the Christmas tree while the child is asleep,” it says:

The stockings are hung by the fireplace (i.e., where Santa enters) and are also filled with small presents and/or treats by Santa upon his arrival. […] Thus, in the minds of young children, Santa Claus’ arrival is denoted by the presence of Christmas presents under the tree and/or Christmas stockings filled with treats.

But the patent soon stumbles upon a lacuna in our Preparatory Equipment for the Arrival of Santa:

However, none of these customary practices, nor any prior art arrangements known to applicant, provides a Christmas stocking which is capable of being selectively illuminated to signal the arrival of Santa Claus.

Egad, they don’t!

Furthermore, there are no such prior art arrangements known to applicant which includes a light, transmissive, three-dimensional, hollow, recognizable character rendition which is capable of being illuminated to signal the arrival of Santa Claus.

Indeed. Some Americans celebrated Christmas for two centuries without ever welcoming a “light, transmissive, three-dimensional, hollow, recognizable character rendition” of a fourth-century saint into their homes. How did they manage?

Well, we have it now and we all get by. And, as the owner of the patent stopped paying its fees sometime over the last two decades, its design has entered the public domain. You, too, can install a Santa Claus Detector in your home, and you won’t even be breaking the law.

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