SALT LAKE CITY (AP) — Utah Gov. Gary Herbert has signed a law banning most abortions after 18 weeks of gestation, setting the stage for a legal showdown.

Herbert spokesman Paul Edwards said Monday the governor is against abortion and believes the law sets an appropriate threshold.

But Planned Parenthood of Utah says it’s clearly unconstitutional. They point to U.S. Supreme Court’s holding that states cannot ban abortion before the fetus is viable outside the womb, at about 23 weeks. The American Civil Liberties Union of Utah has promised to sue.

The law comes as abortion opponents across the country are emboldened by President Donald Trump’s appointment of conservative U.S. Supreme Court justices.

The Arkansas governor has also signed an 18-week ban, and several other states have considered or passed proposals to ban abortion much earlier, once a fetal heartbeat is found.