"We are here today upon the occasion of the 25th anniversary of the United States Supreme Court decision in Roe v. Wade, a decision which ruled unconstitutional a body of State-level laws that proscribed, at least on paper, the performance of most abortions. Most of the laws struck down by Roe had been passed in the last third of the 19th century under social, political, and medical conditions very different from those the Nation has faced in the last quarter of this century, and passage of those laws was pressed by very different forces than those now engaged in the abortion debate."