Image copyright Getty Images Image caption Some believe the patent holder is using a loophole to avoid scrutiny A Native American tribe is suing Amazon and Microsoft for infringing data-processing patents it is holding.
The patents were assigned to the Saint Regis Mohawk Tribe by technology company SRC Labs, and it will receive a share of any award.
Tribal sovereignty means that the patents cannot be reviewed by the Patent Trial and Appeal Board.
A similar deal has drawn criticism from US lawmakers, who claim it is a loophole to avoid patent scrutiny.
Democratic US senator Claire McCaskill drafted a bill this month, in response to another attempt to transfer patents to the same tribe.
In that case, it was pharmaceutical giant Allergan, and a patent for dry-eye medication.
Ms McCaskill said at the time. “Congress never imagined tribes would allow themselves to be used by pharmaceutical companies to avoid challenges to patents, and this bill will shut the practice down before others follow suit.”
The tribe issued a statement questioning why the legislation targeted Native American tribes but not other sovereign governments or state universities.
John Tothill, a partner at law firm Dehns, said the US appeal board was frequently used to revoke patents.
“Microsoft or Amazon could pre-empt this action by applying to have the patents revoked,” he said.
“It is a way of playing the system, if you like, and trying to block potential litigation.
“I am assuming that passing the patents on like this stops that because the US federal government does not have rights over the sovereignty of Native Americans.”
Neither Amazon nor Microsoft have responded to requests for comment.