The efforts of conservative presidents to roll back the civil rights decisions of the 1950's and 60's by appointing conservative justices accomplish little at first, with many appointees thought to be conservative siding with the liberal justices for decisions like Roe v. Wade. A stronger conservative presence emerges when William Rehnquist becomes Chief Justice and Antonin Scalia is appointed to replace Warren Burger. Yet even under Rehnquist, the Court does not overrule Roe v. Wade in Casey v. Planned Parenthood, and strengthens the constitutional status of Miranda in Dickerson v. US. Instead, the Rehnquist court challenges the federal government's powers in U.S. v. Lopez and wades into a political battle in Bush v. Gore.