CHICAGO (AP) — Anti-abortion activists are challenging a Chicago ordinance that stops protesters from getting within 8 feet of anyone entering a health care facility.

The complaint was filed Tuesday in federal court in Chicago by anti-abortion groups and “sidewalk counselors” who want to hand out literature near abortion clinics. They claim the city violates their free speech rights with its 8-foot “bubble zone” around people within 50 feet of clinic entrances.

Abortion rights activists say such laws allow women to seek abortions free of intimidation.

Chicago’s ordinance is similar to a Colorado law the U.S. Supreme Court upheld in 2000. Chicago Law Department spokesman Bill McCaffrey says the city “will vigorously defend against” the lawsuit.

In 2014, the U.S. Supreme Court struck down a Massachusetts 35-foot buffer zone law, prompting other challenges.