A Texas law banning most abortions in the state took effect at midnight, but the Supreme Court has yet to act on an emergency appeal to put the law on hold.If allowed to remain in force, the law would be the most dramatic restriction on abortion rights in the United States since the high court’s landmark Roe v. Wade decision legalized abortion across the country in 1973.The Texas law, signed by Republican Gov. Greg Abbott in May, would prohibit abortions once a fetal heartbeat can be detected, usually around six …