If a New Hampshire man thinks cops lie, he's free to say so on his license plate, the state's highest court ruled Wednesday.

In a unanimous decision, the state Supreme Court agreed with the arguments of David Montenegro, who wanted the vanity plate reading "COPSLIE" to protest what he calls government corruption.

State law prohibits vanity plates that "a reasonable person would find offensive to good taste." But the New Hampshire Civil Liberties Union argued that the law is unconstitutionally vague and gives too much discretion to a person behind a Department of Motor Vehicles counter.

New Hampshire had argued that state workers were right to deny the plate, because the phrase disparages an entire class of people — police officers.

The justices said that state law does not define the phrase "offensive to good taste."

"The restriction grants DMV officials the power to deny a proposed vanity registration plate because it offends particular officials' subjective idea of what is 'good taste,'" the court wrote. The decision states the law is unconstitutionally vague and violates free speech rights.

The case was sent back to Strafford County Superior Court for further proceedings.

Attorney Anthony Galdieri, who argued the case on behalf of Montenegro and the New Hampshire Civil Liberties Union, said he was not surprised by the ruling. "This regulation was an impermissible way to regulate speech under the First Amendment," Galdieri said.