PROVIDENCE — A federal judge has struck down a state law that allowed police chiefs to remove political campaign signs from the side of public roadways at their discretion.

U.S. District Judge William E. Smith ruled that the law unconstitutionally infringed on the freedom of speech by letting police chiefs decide who can post signs, but not listing criteria chiefs should use in making that decision.

Rodney D. Driver, whom Smith described as a perennial candidate for Congress, filed suit after Richmond Police Chief Raymond A. Driscoll removed campaign signs that Driver had placed on private property across the street from the entrance to the Washington County Fair in 2006.

“I thought it outrageous that a police chief could decide who may or may not post political signs, and then tear down those he disapproved of,” Driver said yesterday in a statement issued by the Rhode Island Affiliate of the American Civil Liberties Union, which represented Driver in court.

Driver’s suit targeted a section of state law that bans the placement of political signs — or other markings, including commercial signs and graffiti — in three locations: on traffic signs, on private property without the owner’s consent and in or along public roads without the police chief’s consent.

The state argued in court that the law is needed to prevent signs from encroaching on roadways and becoming a safety hazard.

The judge didn’t see it that way.

“The state’s reading of the statute is overly generous, to say the least,” Smith wrote in a 25-page opinion dated July 31.

“The statute makes no mention of traffic safety, or any other purpose justifying the restrictions, and sets forth no standards based on the characteristics of a proposed sign, i.e. color, size or shape …. It vests chiefs of police with unfettered discretion, unconnected to any standards related to safety or any other legitimate consideration.”

Smith cited a 1969 U.S. Supreme Court decision that held, “An ordinance which … makes the peaceful enjoyment of freedoms which the constitution guarantees contingent upon the uncontrolled will of an official … is an unconstitutional censorship.”

“Ultimately, allowing the statute to stand would be an endorsement of a ‘trust me because I am the Chief of Police’ standard,” Smith wrote. He noted that the Supreme Court rejected that thinking in a 1988 case.

But, Smith noted, restricting the placement of signs near roadways does not, by itself, violate the First Amendment’s guarantee of free speech. Instead, the judge wrote, the law was faulty because it lacked objective criteria for chiefs to apply when deciding on the placement of signs. He observed that further legislation or regulations could bring the statute into compliance with the Constitution.

Driver, a former state representative, this year is seeking to return to the state House of Representatives as a Democrat representing District 39, which includes Richmond, Exeter and Charlestown.

In his statement yesterday, he said he hopes to place campaign signs across from the county fair again this year.

pparker@projo.com