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Oilfield-services company Smith International Inc. is asking a federal judge in Delaware to lift a stay on its patent infringement suit against rival Baker Hughes Inc., arguing that Baker Hughes was taking advantage of long delays for inter partes review in the case.

On Tuesday, Smith’s attorneys asked U.S. District Judge Eduardo C. Robreno to allow the case to resume, after the U.S. Court of Appeals for the Federal Circuit last week ruled that the bulk of the asserted claims on two Baker Hughes’ patents for oil and gas drilling equipment were patentable and subject to a court challenge.

The case has been on hold since July, when Robreno, visiting from the U.S. District Court for the Eastern District of Pennsylvania, pending inter partes review of Baker Hughes’ so-called ’099 patent and the Federal Circuit appeal of the other patent, identified as the ’817 patent in court documents.

In the filing, Smith’s attorneys from Phillips, Goldman, McLaughlin & Hall said that Baker Hughes had twice unsuccessfully urged the U.S. Patent and Trademark Office to review the ’817 patent in an apparent bid to drag out the dispute, which was initially raised in the U.S. District Court for the Southern District of Texas back in 2012. But the appeals court ruling had left “so little at stake” in the inter partes reviews that the case should finally be permitted to proceed to claim construction, the company said.

“[Baker Hughes] has effectively delayed the prosecution of Smith’s patent infringement claims with respect to the ’817 and ’099 patents for over four years, since Smith originally asserted the patents in the Southern District of Texas,” the attorneys wrote. “Yet, despite BHI’s failures in the PTO, BHI has achieved its apparent objective—delaying resolution of this case and running years off the life of the patents.”

Baker Hughes had not responded Wednesday afternoon to Smith’s motion, according to an online docket-tracking service, and an attorney for the company did not return a call seeking comment on the filing.

Smith and its parent company Schlumberger had initially sued Baker Hughes in the Texas federal court in December 2012, in a case that also alleged breach of contract and fraud claims.

But the case languished for three years while the PTO conducted ex parte re-examinations on some of the claims of the two patents. The PTO later concluded that the challenged claims of the ’099 patent were patentable over prior art, but ruled against Smith in rejecting various claims of the ’817 patent as obvious and unpatentable.

Smith appealed the PTO examiner’s rejection to the U.S. Patent Trial and Appeal Board, which affirmed the finding last April. Smith launched its appeal to the Federal Circuit that summer.

Meanwhile, Smith brought stand-alone claims for patent infringement in Delaware district court in January 2016, where last year it fought off Baker Hughes’ attempt to have the case transferred back to Texas.

On Sept. 26, the Federal Circuit returned its ruling in a precedential opinion, which reversed the PTO’s rejection of all claims appealed from the ex parte re-examination and found all of the appealed claims to be patentable.

The ruling, Smith said, meant that only two of the 10 claims briefed for claim construction would potentially be affected by two lingering inter partes reviews for the ’099 patent.

“Continuing the stay has the potential of removing at most only two of 10 claim terms that are currently before the court for construction, and even then, these claim terms will only be impacted if [Baker Hughes] prevails in showing that these two claims are invalid,” the company said.

The case is captioned Smith International v. Baker Hughes.

Tom McParland can be contacted at 215-557-2485 or at tmcparland@alm.com. Follow him on Twitter @TMcParlandTLI.