By Andrew Chung

WASHINGTON (Reuters) – The U.S. Supreme Court on Tuesday tackles a dispute over whether a California law requiring Christian-based facilities that counsel pregnant women against abortion to post signs disclosing the availability of state-subsidized abortions and birth control violates their right to free speech.

The nine justices are set to hear an hour of arguments in an appeal by a group of non-profit facilities called crisis pregnancy centers of a lower court ruling upholding the Democratic-backed 2015 law.

The case represents a crossroads of two contentious issues: abortion and the breadth of the right to freedom of speech under the U.S. Constitution’s First Amendment. The Supreme Court legalized abortion in 1973, and the wider issue of abortion rights is not at issue in the case.

Crisis pregnancy centers say they offer legitimate health services but that it is their mission to steer women with unplanned pregnancies away from abortion. They accuse California of forcing them to advertise for abortion even though they oppose it.

California says some crisis pregnancy centers mislead women by presenting themselves as full-service reproductive healthcare facilities and the law helps ensure these clients are made aware of abortion services available elsewhere.

The San Francisco-based 9th U.S. Circuit Court of Appeals upheld the law in 2016 after it was challenged by some of these facilities, finding the statute did not discriminate based on viewpoint.

California’s Reproductive FACT Act, passed by a Democratic-led legislature and signed by Democratic Governor Jerry Brown, requires centers licensed as family planning facilities to post or distribute notices that the state has programs offering free or low-cost birth control and abortion services. The law requires unlicensed facilities with no medical provider on staff to disclose that fact.

Abortion rights advocates say the roughly 2,700 U.S. anti-abortion pregnancy centers, including around 200 in California, far outnumber facilities providing abortions.

The California challengers are the National Institute of Family and Life Advocates, an umbrella group for crisis pregnancy centers, and two such facilities in San Diego County. The plaintiffs had told the lower courts that they would not comply with the law.

A win for them could make it harder for Democratic-governed states to impose rules on crisis pregnancy centers, but also could help abortion rights advocates challenge laws in Republican-governed states that impose certain requirements on abortion clinics.

California said its law does not force crisis pregnancy centers to refer women for abortions, nor does it prevent them from voicing their views on abortion. The state told the justices in legal papers that some centers use incomplete or false medical advice to try to prevent women from having an abortion. Some resemble medical clinics, down to lab coats worn by staff, to try to confuse women into thinking they are at a center offering all options, the state added.

The facilities deny using deceptive tactics.

A ruling is due by the end of June.

(Reporting by Andrew Chung; Editing by Will Dunham)