"[W]e decide, based on the evidence properly before us, that these registrations must be cancelled because they were disparaging to Native Americans at the respective times they were registered," said the USPTO's Trademark Trial and Appeal Board in a ruling released Wednesday morning.
Federal trademark law does not allow the registration of trademarks that disparage certain groups.
The case was filed in 2006 against Pro Football Inc. by five Native American activists: Amanda Blackhorse, Phillip Glover, Marcus Briggs-Cloud, Jillian Pappan and Courtney Tsotigh.
The activists insisted the term was an ethnic slur, a claim that the team has rejected.
"We are extraordinarily gratified to have prevailed in this case,” said Alfred Putnam Jr., chairman of Drinker Biddle & Reath law firm, which represented the plaintiffs. He added that the case would set a "historic precedent."
Redskins owner Dan Snyder has repeatedly rejected calls to change the team's name. He has cited the team's long history as a source of pride for the D.C. metro region as the reason.
Snyder has not yet issued a statement in reaction to the ruling.
The USPTO's decision was not entirely unexpected. In January, it rejected an effort to trademark the name "Redskins Hog Rinds" for a snack food, stating then that the term was offensive.
The ruling applies not just to the name but some of the Imagery the team has trademarked as well, such as the stylized profile of a Native American used in connection with the team. In all, six trademarks were cancelled.
Revoking the trademark does not prevent the team from continuing to use the name, but it will have substantially less control over its use.
The team can still claim legally that it has exclusive rights to use the name based on the length of time that it has used it.
Proving that in court will not be as easy, though, as a defendant can point to the trademark decision as a defense.