UPDATE 1-U.S. Supreme Court upholds legality of patent review process

(Adds background to case, two conservative justices dissent, paragraphs 3, 5-6)

WASHINGTON, April 24 (Reuters) - The U.S. Supreme Court on Tuesday gave its stamp of approval to a government review process prized by high technology companies as an easy and cheap way to combat "patent trolls" and others that bring patent infringement lawsuits.

The justices ruled 7-2 that a type of in-house patent review at the U.S. Patent and Trademark Office does not violate a defendant's right under the U.S. Constitution to have a case adjudicated by a federal court and jury. The court ruled against Oil States International Inc, a Houston-based oilfield services company that had challenged the legality of the process, called inter partes review (IPR).

Conservative Justices John Roberts and Neil Gorsuch dissented from the decision to uphold the reviews.

While the ruling gave Silicon Valley reason to celebrate, it was sure to displease name-brand drugmakers, which had called the IPR process a threat to innovation.

The U.S. Congress created the reviews as part of a 2011 law to deal with the perceived high number of flimsy patents that had been issued by the patent office in prior years. Since then, the patent office's Patent Trial and Appeal Board has canceled all or part of a patent in about 80 percent of its final decisions. In 2015, it canceled an Oil States patent on protecting wellhead equipment after an IPR proceeding.

These reviews have been especially popular with companies like Apple Inc and Samsung Electronics Co Ltd that are frequent targets of patent infringement suits. On the other hand pharmaceutical companies like AbbVie Inc, Allergan plc and Celgene Corp called for the IPR system to be scrapped.

(Reporting by Andrew Chung; Editing by Will Dunham)