Indiana's highest court heard arguments Thursday on whether a police officer was wrongly denied a vanity license plate saying '0INK,' which state officials had deemed offensive.

Solicitor General Thomas Fisher told the Indiana Supreme Court that the Bureau of Motor Vehicles has the right to reject offensive messages sought on personalized license plates. Indiana revoked the officer' plate, just as it could deny a request for a plate bearing a racial slur, he told the justices.

"Every license plate has government speech on it," Fisher argued. "The BMV needs discretion to operate this program successfully."

The American Civil Liberties Union of Indiana, which is representing Greenfield police Officer Rodney Vawter, says the BMV made an arbitrary decision that violates free speech rights. Ken Falk, the ACLU's legal director, cited plates the BMV has allowed that also might be deemed offensive, such as "BLK JEW," ''HATE" and "FOXY GMA."

Vawter sued the BMV in May 2013 after it revoked his plate after three years, which featured a zero followed by the letters "INK," meant to be a tongue-in-cheek reference to his job.

In its arguments, the state cited a statute allowing it to refuse to issue a plate deemed "offensive to good taste and decency" or that "would be misleading." But a Marion County judge ruled in Vawter's favor, saying the BMV lacks consistent rules for determining what is and isn't appropriate and directed the agency to come up with new guidelines.

That process is on hold pending the outcome of the case. The BMV also stopped offering vanity plates in 2013 until the case was decided.

To bolster the state's case, Fisher cited a recent U.S. Supreme Court ruling that found Texas did not violate the free speech rights of some residents by refusing to issue a license plate featuring the Confederate battle flag. Texas had argued that the license plates are government property, and so what appears on them is not private individuals' speech but the government's.

Falk, who also appeared on behalf of a client whose revoked vanity plate said "UNHOLY" — a reference to a song by the rock group KISS — noted that the state has sanctioned religious-themed plates and questioned if it was using a double standard that violates freedom of religion protections.

"Clearly, if you are going to allow people to have 'BIBLE 4 ME' or 'GOD THANKS' you have to allow 'UNHOLY,' " Falk said. "You can't pick and choose sentiments."

The justices did not take action on the case Thursday, and there's no schedule for a ruling.