Regular Switch readers know the United States Court of Appeals for the Federal Circuit as the court that is largely responsible for the patent crisis, due to its consistent bias in favor of patent owners and its enthusiasm for software patents. But the Federal Circuit's influence — and its pro-plaintiff tilt — extend much further. It has a large trademark docket because it hears appeals from the trademark side of the Patent and Trademark Office, and it sticks its fingers in copyright law with some regularity.

The Federal Circuit has done the most damage to design patent law. Unlike regular (or "utility") patents, which cover the useful aspects of inventions, design patents are intended to cover the purely "ornamental" features of products. For decades, design patent law was an intellectual property backwater: the PTO hands out 10 times more utility patents than design patents each year.

The nation's top patent court has been on a Frankenstein-like quest to reanimate design patent law, stitching together pieces of patent law, copyright law and even trademark law into an unnatural monster. In the past few years, and particularly in a 2008 case called Egyptian Goddess (not involving an actual goddess), the Federal Circuit has made it substantially harder for defendants to show that a design patent should never have been granted in the first place.

Its decision Thursday in a case called High Point Design v. Meljer shows how useless its few remaining tests are at screening out junk design patents.

The case involved the "Snoozies" style of fur-lined slippers. The plaintiff had a design patent on them, which should have meant two things: first, that the design wasn't "obvious" in light of previous fur-lined slippers, and second that the design really was ornamental rather than "functional." (Useful features are for regular patents, which are much harder to obtain; design patents are only supposed to cover the useless decorations.) Snoozies' owner sued the makers of "Fuzzy Babba" slippers, which are sold at Sears and Wal-Mart.

Even a moment's glance at the Snoozies design patent shows that someone was asleep on the job at the Patent Office when it was issued. In the words of Georgetown law professor Rebecca Tushnet, "I'm baffled by how anyone could look at that and see anything but a basic fur-lined slipper." The trial court also saw a basic fur-lined slipper, and invalidated the patent. But the Federal Circuit reversed and sent the patent back for another look.

The trial court found that the Snoozies fur-lined slipper design was obvious in light of an earlier fur-lined slipper, the Penta, which it described as "indistinguishable." The Federal Circuit threw out this reasoning, because the trial court failed "to translate the design of the ’183 patent into a verbal description' " and did not provide "sufficient detail to its verbal description of the claimed design to evoke a visual image consonant with that design." Even though design patents are described using pictures, the Federal Circuit's obviousness test is literally blind; only detailed descriptions using words are acceptable.

The trial court's entirely sensible conclusion that the patent was invalid because the Snoozies' fur lining was "functional" fared no better. According to the Federal Circuit, it was a mistake to ask whether the design's "primary features" are functional; instead, the right question is whether the design is "primarily functional." This distinction makes no sense in the context of the case: There is literally nothing to the Snoozies design other than fur and a slipper.

The Federal Circuit doesn't generally see itself as a pro-patentee court. It thinks of itself as developing a rigorous and intellectually coherent body of law, which it applies even-handedly. But in the words of U.C. Irvine law professor Dan Burk, the result is a "clockwork lemon": a "a wonderfully intricate and very precise axiomatic framework" that "bears no relationship to the actual needs" of the industries it affects. Like its utility patent doctrines, the Federal Circuit's design patent doctrines systematically uphold patents that should never have been granted in the first place, giving trolls and titans the ability to extort settlements and muscle out the competition.

Its intellectual property decisions aren't all bad. In copyright, the court is responsible for important opinions making open source licenses enforceable and rejecting the misapplication of copyright law to garage door openers. But for every good decision, there is a howler. In 2010, the Federal Circuit reversed a lower court and held that a Postal Service stamp infringed sculptor Frank Gaylord's copyright in the Korean War Veterans Memorial. The stamp used a haunting photograph of the memorial in the snow, but the Federal Circuit ruled that the stamp wasn't a legal fair use because it had the same purpose as the memorial: "to honor veterans of the Korean War." Gaylord was awarded $685,000 in the case Friday.

The Supreme Court can, and regularly does, correct the Federal Circuit's mistakes. But the Supreme Court can't shine its light everywhere at once, and the Federal Circuit's design patent, trademark, and copyright case law have been festering in the darkness. Ultimately, only Congress can solve the problem by rolling back the Federal Circuit's jurisdiction and taking more intellectual property cases away from it.

James Grimmelmann is a professor of law and the director of the Intellectual Property Program at the University of Maryland.