Mercedes Benz can continue installing in its vehicles a device that detects and rouses drowsy drivers, thanks to a federal judge’s dismissal of a patent- infringement suit.

The plaintiff in Ibormeith IP LLC v. Mercedes-Benz USA, 10-cv-5378, claimed Mercedes’ “attention assist” system, implemented in certain vehicles since 2009, infringed on a 2001 U.S. patent called “Sleepiness Detection For Vehicle Driver or Machine Operator.”

Mercedes’ attention-assist system observes driver behavior during the first few minutes of a trip and continually compares that data with data compiled from sensors throughout the trip. The main metric is steering-wheel movement. The system also monitors speed, acceleration, use of pedals and directional indicators, and wind and road conditions. When driving behaviors indicate fatigue, the system emits an audible signal and a lighted warning in the dash.

The patent, which Ibormeith IP, of Longview, Texas, a nonpracticing entity, acquired from the original inventors, describes a sensor that would monitor factors like road condition, cabin temperature, steering and acceleration, and even take into account the individual driver’s circadian patterns.

Mercedes contended in an April 25 hearing that several aspects of the patent are indefinite under 35 U.S.C. 112, which requires inclusion of “one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.”

On Wednesday, U.S. District Judge Faith Hochberg, sitting in Newark, agreed and dismissed the suit, holding that Mercedes proved by clear and convincing evidence that the patent is indefinite and unenforceable.

When a patent lays out a function or functions implemented by a computer — such as the monitoring device — it must disclose the algorithm used to carry out the function, Hochberg noted, citing a decision by the U.S. Court of Appeals for the Federal Circuit issued just weeks before the hearing, Noah Sys., Inc. v. Intuit Inc., 675 F.3d 1302.

Ibormeith’s patent includes an equation (the “sleep propensity algorithm”) that combines several factors — such as light and temperature conditions, steering angle and duration of the trip — to determine the likelihood of sleepiness, measured by a number ranging from zero to one. But the patentee “chose not to explain or discuss the often Byzantine tables” used as an attempt to explain the equation, Hochberg said.

“The choice not to discuss such a vast array of unexplained tables does not meet the burden of a patentee” to link the computer with its claimed function, and “also makes it difficult for a potential infringer to understand the boundaries of the patent’s claims,” she wrote.

The patent also does not explain how the system would obtain scores for each factor or weight them against one another, Hochberg said.

“For the patent to state that the tables ‘are generally self-explanatory and will not otherwise be discussed’ is simply remarkable,” the judge wrote, calling the equation “a list of unremarkable factors that can cause driver sleepiness” which “contains the kernel of an idea for a weighting formula.”

Ibormeith contended that not all the factors in the equation must be used, and one step in the algorithm is choosing which to employ, but Hochberg noted that the patent does not reflect that, and should have, if it were the case.

The patent also does not explain how the device would “produce an output,” or actually alert the driver to a drowsiness warning, Hochberg says. “Disclosing that a warning thresholds exist … does not constitute a sufficiently detailed disclosure of how the computer uses that score to determine when a warning should be issued.”

Hochberg noted that since she determined that the patent fails to disclose any algorithm, she need not consider the parties’ expert testimony on algorithm comprehensibility. Nonetheless, she added that Ibormeith’s expert “failed to refute certain deficiencies in the patent’s disclosure pointed out by Mercedes.”

Any appeal by Ibormeith would be before the Federal Circuit, which handles all patent appeals.

Stephen Buckingham of Lowenstein Sandler in Roseland, Mercedes’ local counsel, says Hochberg “did a fabulous job understanding complex technology and reached the right result.”

He deferred any additional comment to Scott Doyle of Shearman & Sterling in Washington, D.C., Mercedes’ lead counsel, who says only that he is “pleased with the result.”

Arnold Calmann of Saiber in Newark, Ibormeith’s counsel, did not return a call.