(Reuters) - Relatives of the late conservative activist Phyllis Schlafly on Monday lost their appeal to block a St. Louis, Missouri, craft brewery from trademarking the Schlafly name.

In a 3-0 decision, the U.S. Federal Circuit Court of Appeals ruled in favor of Saint Louis Brewery LLC, which was co-founded by Schlafly’s nephew Thomas Schlafly, and had applied in 2011 to trademark the Schlafly name.

Circuit Judge Pauline Newman said the name had acquired a “secondary meaning” and “distinctiveness” through sales of Schlafly-branded beer, and that surnames could be trademarked when that occurred.

The brewery began selling beer with the Schlafly logo in 1991, and sales had reached 74.8 million cans, bottles and draft servings between 2009 and 2014.

Phyllis Schlafly and her son Bruce Schlafly, an orthopedic surgeon, had claimed that trademarking the Schlafly name for beer could hurt their reputations by associating them with alcohol.

Their lawyer Andrew Schlafly, of Far Hills, New Jersey, who is also a son of Phyllis Schlafly, said his clients plan to appeal to the U.S. Supreme Court.

“It’s unusual for a company to try to trademark a prominent surname such as this,” Andrew Schlafly said in an interview. “The law says words that are ‘primarily merely a surname’ should not be trademarked.”

Mark Sowers, a lawyer for the brewery, did not immediately respond to requests for comment.

The decision upheld an August 2016 ruling by the U.S. Trademark Trial and Appeal Board.

Phyllis Schlafly founded the conservative Eagle Forum and was a forceful opponent of abortion, Communism and adding an Equal Rights Amendment to the U.S. Constitution.

She died in Sept. 2016 at the age of 92. A trust in her name was substituted as a plaintiff in the lawsuit.

The case is Schlafly et al v Saint Louis Brewery LLC, Federal U.S. Circuit Court of Appeals, No. 2017-1468.