The US Supreme Court declined on Monday to hear arguments that a Pittsburgh rapper’s First Amendment rights were violated after he was convicted for song lyrics.

Jamal Knox, who rapped under the name Mayhem Mal, argued that his conviction for song lyrics about killing two police officers violated his First Amendment right.

Knox was charged with several offenses after he fled during a routine traffic stop, which led officers to discover 15 stamp bags contenting heroin, a large some of cash and a loaded firearm in the vehicle Knox was driving. While the charges were pending, Knox co-wrote and recorded a rap song entitled, “F–k the police,” which was later uploaded to YouTube. The song lyrics described killing two Pittsburgh police officers, “Officer Zeltner” and “Mr. Kosko,” two police officers who had participated in Knox’s earlier arrest and were scheduled to testify against him. Knox was convicted in 2013 on state charges of terroristic threats and witness intimidation.

Knox petitioned the high court after the Pennsylvania Supreme court upheld the trial court’s decision that the lyrics constituted a “true threat.” The Pennsylvania Supreme Court reasoned that the First Amendment “permits the imposition of criminal liability based on the publication of a rap-music video containing threatening lyrics directed to named law enforcement officers.”

In his appeal, Knox argued that the Supreme Court needed to resolve the issue of whether the government in a criminal threat case must only prove the “speaker’s subjective intent to threaten,” or must prove “objectively that a reasonable person would regard the statement as threatening.”

In an earlier decision, the Supreme Court ruled in Watts v. United States that “true threats” were outside of the First Amendment’s protections. However, the court failed to clearly establish the level of intent that is necessary in order to determine what constituted a “true threat.”