York County Sheriff William King Jr. has sued the York County Commissioners, accusing the board of illegally slashing his annual salary by more than $15,500 after he took office in January.

King is represented in the lawsuit by state Rep. Mark Dion, an attorney and former Cumberland County sheriff, who said he personally wrote an existing law that prohibits county commissioners from doing what occurred in York County.

“This is black-letter law. Either they followed the statute or they didn’t,” Dion said Tuesday, a day after filing the lawsuit in Cumberland County Superior Court. “They failed to follow the statutory language, and we want back pay.”

Before being elected sheriff in a three-way race in 2014, King worked under former Sheriff Maurice Ouellette as Ouellette’s chief deputy. Ouellette’s annual salary when he retired at the end of 2014 was $93,537, and King’s annual salary as chief deputy was $78,000.

But when King took office as sheriff, the county commissioners continued to pay him at the same rate as when he was chief deputy, even though the amount budgeted for the position remained the same as what Ouellette was paid, the lawsuit states. King was not told of the pay cut before the election.

“Sheriff King presented his concerns to the board and the county manager, Greg Zinser, about the apparent unilateral reduction to the set budgeted salary, in both public and private meetings,” Dion wrote in the lawsuit. “Subsequently, Sheriff King learned that the board had, in fact, unilaterally reduced the set salary for the county sheriff to $78,000. Sheriff King continued to press his objections through the means articulated by the board.”

The commissioners took up the issue at regular meetings, first on May 20 and again on June 3, when it voted to set King’s annual salary at $88,000, according to the board’s minutes.

Dion said he wrote the current law prohibiting cutting a sheriff’s pay after he or she is elected in response to a move by the Piscataquis County Commissioners in 2010 to cut Sheriff John Goggin’s pay by nearly $10,000.

“The salary for the county sheriff must be set prior to the election of a new county sheriff by the board of county commissioners by final budget approval prior to the first date that applicants may file with the Secretary of State for the office of county sheriff,” the current law states. “The salary of the county sheriff may not be reduced during the sheriff’s term other than upon complaint of malfeasance, misfeasance, neglect, gross negligence or failure to maintain certification with the Maine Criminal Justice Academy by the board of county commissioners to the Office of the Governor.”

Dion said he sent a letter July 7 to Zinser and Commissioner Sallie Chandler, the board chairwoman, offering to meet and discuss the law he wrote and his intent in drafting the law, but he received no reply.

“What we’re asking the judge to determine is whether the statute in question was properly applied. And if it was not, we are ordering the county commissioners to abide by the language of the statute and pay back pay,” Dion said. “It’s a pretty straightforward question for the court.”

King declined to comment on the lawsuit, deferring all questions to Dion.

Attorney Gene Libby, who represents the county commissioners, said Tuesday that he had not yet seen the lawsuit and could not comment.

Zinser did not respond to a message seeking comment.

Dion said he filed the lawsuit in Cumberland County rather than York County because he usually practices law in Portland and because it is a neutral venue.