A lone engineer has succeeded in doing what Uber's top lawyers and expert witnesses could not—overturning most of a foundational patent covering arch-rival Waymo's lidar laser ranging devices.

Following a surprise left-field complaint by Eric Swildens, the US Patent and Trademark Office (USPTO) has rejected all but three of 56 claims in Waymo's 936 patent, named for the last three digits of its serial number. The USPTO found that some claims replicated technology described in an earlier patent from lidar vendor Velodyne, while another claim was simply "impossible" and "magic."

Swildens, who receives no money or personal advantage from the decision, told Ars that he was delighted at the news. "The patent shouldn't have been filed in the first place," he said. "It's a very well written patent. However, my personal belief is that the thing that they say they invented, they didn't invent."

The 936 patent played a key role in last year's epic intellectual property lawsuit with Uber. In December 2016, a Waymo engineer was inadvertently copied on an email from one of its suppliers to Uber, showing a lidar circuit design that looked almost identical to one shown in the 936 patent.

The patent describes how a laser diode can be configured to emit pulses of laser light using a circuit that includes an inductor and a gallium nitride transistor. That chance discovery helped spark a lawsuit in which Waymo accused Uber of patent infringement and of using lidar secrets supposedly stolen by engineer Anthony Levandowski.

In August 2017, Uber agreed to redesign its Fuji lidar not to infringe the 936 patent. Then, in February 2018, Waymo settled the remaining trade secret theft allegations in exchange for Uber equity worth around $245 million and a commitment from Uber not to copy its technology. "This includes an agreement to ensure that any Waymo confidential information is not being incorporated in Uber… hardware and software," said a Waymo spokesperson at the time.

That redesign now seems to have been unnecessary, says Swildens, the engineer who asked the USPTO to take a closer look at 936. "Waymo's claim that Uber infringed the 936 patent was spurious, as all the claims in the patent that existed at the time of the lawsuit have been found to be invalid," he said.

Uber told Ars that despite the ruling, it would not be redesigning its lidars yet again.

Just an interested bystander

Remarkably, Swildens does not work for Uber or for Velodyne, nor for any other self-driving developer—he works for a small cloud computing startup. Swildens became interested in the patent when it surfaced during the Uber case, and he saw how simple Waymo's lidar circuit seemed to be. "I couldn't imagine the circuit didn't exist prior to this patent," he told Wired last year.

Swildens' research uncovered several patents and books that seemed to pre-date the Waymo patent. He then spent $6,000 of his own money to launch a formal challenge to 936. Waymo fought back, making dozens of filings, bringing expert witnesses to bear, and attempting to re-write several of the patent's claims and diagrams to safeguard its survival.

The USPTO was not impressed. In March, an examiner noted that a re-drawn diagram of Waymo's lidar firing circuit showed current passing along a wire between the circuit and the ground in two directions—something generally deemed impossible. "Patent owner's expert testimony is not convincing to show that the path even goes to ground in view of the magic ground wire, which shows current moving in two directions along a single wire," noted the examiners dryly.

In September, the axe finally dropped. With a few exceptions, those claims that were not physically impossible were found to have replicated lidar circuits found in pre-existing patents, in particular one called 558 issued to Dave Hall, founder of lidar-maker Velodyne. Swildens says that he's unsurprised by the result and considers his money well spent. "As I investigated the 936 patent, it became clear it was invalid due to prior art for multiple reasons," he says. "I only filed the reexamination because I was absolutely sure the patent was invalid."

Waymo declined to comment on the record, but the company could now find itself in an awkward position. In 2017, Waymo CEO John Krafcik stood up at the Automobili-D conference in Detroit and announced that his company, which had previously bought dozens of lidars from Velodyne, was now designing and building all of its sensors in-house and "from the ground up."

Krafcik went on to deliver some sly digs at his former supplier. "Designing our own lidar system has not only given us a more reliable product than what we can get off the shelf, but it's enabled us to do it at a fraction of the cost," he said. "Just a few years ago, a single top of the range [Velodyne] lidar unit would have cost $75,000. Today, we've brought that cost down by more than 90 percent."

The USPTO's findings call that narrative into question, believes Swildens. "The design of the Waymo lidar appears to be based on the design of the Velodyne lidar units they had been using," he says. "As part of this, Waymo utilized circuitry similar to Velodyne circuitry and then attempted to patent (and did patent) those circuit designs as their own novel inventions."

Pot, meet kettle?

In its original lawsuit against Uber, Waymo wrote: "Waymo developed its patented inventions… at great expense, and through years of painstaking research, experimentation, and trial and error. If defendants are not enjoined from their infringement and misappropriation, they will cause severe and irreparable harm to Waymo." If Velodyne believes that its 558 patent covers lidars that Waymo is now on the point of commercializing, it could make a similar complaint in court itself.

However, the situation is complicated by the fact that Velodyne is currently embroiled in its own patent dispute with a startup called Quanergy that is developing solid-state lidars. Velodyne has accused Quanergy of infringing its intellectual property, while Quanergy in turn claims that Velodyne's original 558 patent is itself invalid.

Velodyne is attempting to shore up 558 by rewriting it, but judges in the case noted in a recent filing that there was "a reasonable likelihood" that at least one of its claims is also unpatentable. Velodyne did not respond to requests for comment.

Self-driving startups should not take this legal confusion as carte blanche to use the lidar technology described in Waymo's and Velodyne's patents, warns Brian Love, co-director of the High Tech Law Institute at the Santa Clara University School of Law. "There's a joke among patent lawyers that a final rejection is anything but final, because owners still have options even after a final rejection," he tells Ars. "And to get an award in a patent action, you only have to show infringement of one claim in one patent. The fact that there's even one claim left in Waymo's patent means there's one shot for arguing that someone infringes that claim."

Waymo also has hundreds of other patents developed in-house, or bought from rivals. They might not all contain the "magic" claims of 936, but they are probably enough to keep Waymo in the driving seat of autonomous vehicles for some time—especially as Swildens says he's too busy right now to issue any more patent challenges.