The Supreme Court said Wednesday that the state of West Virginia unlawfully discriminated against a retired U.S. marshal when it excluded him from a more generous tax break given to onetime state law enforcement officers.

The court ruled unanimously for retired marshal James Dawson.

West Virginia law exempts state law enforcement retirees, including former policemen and firefighters, from paying income tax on their retirement benefits. But retired U.S. Marshals Service employees such as Dawson haven’t been getting that tax advantage.

Justice Neil Gorsuch wrote that because there aren’t any significant differences between Dawson’s former job responsibilities and those of state law enforcement retirees, “we have little difficulty concluding” that West Virginia’s law unlawfully discriminates against Dawson under federal law.

West Virginia had argued that it wasn’t doing anything wrong and that Dawson was getting the same benefit, a $2,000 income tax exemption, that applies to virtually all retired federal, state and local employees in West Virginia. The state said that only a “surpassingly small” number people who participate in specific, state-managed retirement plans get the exemption Dawson wanted to claim.

The U.S. government had backed Dawson, who served in the U.S. Marshals Service from 1987 to his retirement in 2008. He led the Marshals Service in the Southern District of West Virginia for the past six years.

In 2013, he filed paperwork seeking to amend his tax returns for two years and claim the more favorable tax exemption. Dawson said the state owed him $2,174 for 2010 and $2,111 for 2011. State tax officials disagreed, so Dawson took his case to court.