Out of our Top 20, whom do you like best?

Kathleen Sullivan, 53, is the former dean of Stanford Law School, teaches constitutional law there, and has authored the nation's leading constitutional law casebook. She is chair of the National Appellate Practice at Quinn Emanuel Urquhart Oliver & Hedges. A one-time Marshall scholar, Sullivan's constitutional knowledge is prodigious. Her former law professor Laurence Tribe once called Sullivan "the most extraordinary student I had ever had." The National Law Journal has twice named her one of the "100 Most Influential Lawyers in America" and has twice named her as one of the "50 Most Influential Women Lawyers in America." Today Politico reported that she was a lesbian; she did not comment.

Sullivan is a gifted oral advocate and has argued five cases at the Supreme Court, notably several important business cases in recent years, including an appeal representing wineries challenging bans on the direct shipment of wine to consumers living out of state. She was also a member of the legal team that challenged the McCain-Feingold campaign finance law. Sullivan has filed amicus briefs in two seminal gay rights cases at the Supreme Court, Lawrence v. Texas and Bowers v. Hardwick, and authored an amicus brief in a case involving the constitutionality of gay marriage in California. She is also well-known for her pro bono work in high-profile cases involving civil rights and civil liberties. In a brief she co-authored in a landmark case about warrantless NSA wiretapping, she wrote, "Whatever inherent powers the President might have under Article II, they do not include the power to conduct a warrantless domestic surveillance campaign, of indefinite duration and unlimited scope, where a duly enacted statute expressly prohibits such conduct." (Disclosure: Sullivan was a professor of Dahlia Lithwick's at law school.)

Margaret McKeown, who is about to turn 58, was the first woman partner at the Seattle law firm Perkins Coie, where her 23-year practice concentrated on antitrust and intellectual property law and her clients included Boeing and Citicorp. Bill Clinton nominated her to the 9^th Circuit in 1996. After Republicans refused to bring the nomination to a vote, Clinton had to nominate her again in 1997. In the end, she was confirmed by a wide margin of 80-11.

McKeown's nomination ran into trouble, initially, because of her pro-bono legal work for the Washington Association of Churches. In 1994, she helped the mainstream church group work with the ACLU in trying to declare unconstitutional two citizen initiatives, written to deny gay people protection from discrimination based on sexual orientation.

McKeown also came under attack from conservatives for signing a resolution urging the American Bar Association to support Roe v. Wade.

Notable cases: In 2007, McKeown wrote the 9^th Circuit opinion that barred an Islamic charity from showing, with a confidential government document, that the National Security Agency had wiretapped its offices without a warrant. McKeown accepted "the need to defer to the executive on matters of foreign and national security" and wrote that judges "surely cannot legitimately find ourselves second-guessing the executive in this arena." She rejected, however, the Justice Department's argument that "the very subject matter" of the litigation was a state secret—a position the Obama administration has continued to take.

In 2007, McKeown pushed the Bush EPA to update its water-pollution guidelines under the Clean Water Act, by recognizing the effect of new technology. The EPA position that it did not have to take new technology into account "strains credulity to the breaking point," McKeown wrote. In the famed challenge to the Pledge of Allegiance that came before the 9^th Circuit, McKeown voted for a rehearing of the three-judge panel ruling that under God in the pledge violated the Constitution's separation of church and state. McKeown did not say that she thought the panel had gotten the case wrong but that it presented "a constitutional question of exceptional importance."

Hillary Clinton, 61, was active in law for two decades between graduating from Yale Law School in 1973 and moving to Washington as first lady in 1993. After a brief stint working for the House judiciary committee on the impeachment of President Richard Nixon, she moved to Arkansas to reunite with law school flame Bill Clinton, where she taught at the University of Arkansas law school and joined the Rose Law Firm. She became the first female partner there in 1979 and continued to practice during Bill Clinton's tenure as governor. She has remained in Washington for the last 16 years, including eight as the junior senator from New York and now as Obama's secretary of state.

Much of Clinton's early work was devoted to advocacy for children, including championing the Children's Defense Fund. She co-founded the Arkansas Advocates for Children and Families. Her first scholarly article, published in the Harvard Educational Review, was titled "Children Under the Law" and argued that children should not be categorically treated as incompetent to make legal decisions up until their 18^th birthdays. (She elaborated on this topic in future articles, stating that courts should intervene in family cases only in extreme circumstances but that children in such cases should be treated as gradually more independent as they mature.)

At the Rose Law Firm, Clinton focused on intellectual property and patent infringement cases. She also worked in business litigation, including work for Wal-Mart and TCBY. (It was also at Rose that she billed 60 hours of work to Madison Guaranty, which later became a subject of intense scrutiny during the Whitewater investigation.) The National Law Journal twice named her one of the 100 most influential American lawyers. If Clinton were to get the nod, her pro-choice record would be scrutinized—along with plenty of other positions she has taken on the campaign trail.