One of the Supreme Court's more interesting internal dynamics is the intellectual sparring between two former law professors, Justices Antonin Scalia and Stephen G. Breyer.

Scalia, the conservative, wants the court's interpretations of the law to stick as closely as possible to the text of statutes and the original meaning of the Constitution; Breyer, the liberal, argues just as forcefully that this approach is narrow and impractical. It's a battle of ideas that has been waged in their opinions, their remarks at oral argument -- even in a televised debate at American University in January.

Now Breyer has taken his side of the argument to the next level, publishing a book called "Active Liberty: Interpreting Our Democratic Constitution" about how justices should decide cases. It is based on speeches he gave as the Tanner Lectures on Human Values at Harvard University last year -- just as Scalia's 1997 manifesto, "A Matter of Interpretation: Federal Courts and the Law," was based on Scalia's 1994-1995 Tanner Lectures.

Breyer's thesis is that justices must be guided by the broad democratic purposes embodied in the Constitution's various provisions, rather than its words alone. As an example, he writes that campaign finance regulations are constitutional because they "help further the kind of open public discussion that the First Amendment seeks to sustain, both as an end, and as a means of achieving a workable democracy."

In an interview about his book, Breyer said that it is not a direct riposte to Scalia's but acknowledged, "I have to, of course, describe the views of those who disagree with my approach."

Breyer laughed when told that Amazon.com's page on "Active Liberty" reports that "customers who bought this book also bought" the Scalia opus. Recently the Web site offered the two as a package deal for about $26.00. "Good -- it's a bargain!" Breyer joked.

Breyer thinks judges should consider the possible social consequences of their decisions -- unlike Scalia, who says that is a recipe for judicial policymaking.

"Consequences are highly relevant," Breyer said in the interview. "Not just any consequences but consequences in light of a constitutional value. . . . You can be wooden and mechanical, and the price you'll pay is a law that won't fulfill the basic principles of the Constitution, which is to help people live together in a democratic society."

Justices Antonin Scalia, left, and Stephen G. Breyer debated at American University in January. Breyer's tome on his views joins Scalia's 1997 work at bookstores.