(AP) — The Justice Department is challenging a ruling that an abortion opponent’s letter to a Wichita doctor saying someone might place an explosive under her car is constitutionally protected speech.

The department’s Civil Rights Division filed a notice Thursday saying it plans to appeal to the 10th Circuit Court of Appeals a federal judge’s decision that the letter from Angel Dillard did not constitute a “true threat” under the law. The government sued Dillard in 2011 under a law aimed at protecting access to abortion services.

U.S. District Judge J. Thomas Marten decided the case in Dillard’s favor amid secret filings. The judge also refused the government’s request to unseal court documents.

Marten wrote that the government supplied no evidence that actual violence against Dr. Mila Means was likely or imminent.