The Supreme Court on Monday agreed to take up a dispute over a Mississippi law that bans virtually all abortions after 15 weeks of pregnancy, potentially setting the 6-3 conservative majority court on a collision course with the landmark 1973 decision in Roe v. Wade. The move was announced in an unsigned order, with the justices indicating the dispute would be limited to the major issue of the constitutionality of pre-viability restrictions on elective abortions.