Massachusetts' highest court will hear a challenge to the state's criminal harassment law from a man convicted of sending profanity-laced letters to a local elected official.

Harvey Bigelow, of Rehoboth, was convicted of writing letters to Selectman Michael Costello and his wife in 2011. The letter writer called Costello a "scumbag," ''loser" and other names. The writer also accused Costello of attempting to kill his ex-wife and abusing drugs and alcohol.

Bigelow denies writing the letters. In an appeal, his lawyer argues that the remarks were "merely political hyperbole" to express dissatisfaction with Costello's job performance and weren't "true threats." She says the letters constitute free speech.

Prosecutors say the letters included "a large amount of threatening, ominous, and intimidating material."

The Supreme Judicial Court will hear arguments Jan. 8.