On April 17, 1905, the United States Supreme Court declared that a New York law prohibiting the employees of bakeries from working more than 10 hours a day or 60 hours a week was unconstitutional.

For the majority, Justice Rufus Peckham argued that the New York law violated the "right of contract" that was protected by the Fourteenth Amendment of the Constitution. The court acknowledged that the states, in the exercise of their "police power," could regulate certain conditions of labor. But baking, it said, was not a hazardous occupation and bakers were not stupid or passive workers. They should therefore be left "free" to make contracts "upon such terms as they think best." Laws such as the one in New York were "meddlesome interferences with the rights of the individual," specifically the "liberty of contract."

The case, Lochner v. New York, quickly became famous as much for the dissent of Justice Oliver Wendell Holmes as for any practical effect the decision might have had. (It was substantially overruled three years later.) Holmes said, rightly, that the court had long deferred to the judgment of state legislatures in regulating the conditions of life. He mentioned laws forbidding usury, prohibiting lotteries, compelling schooling and vaccinations, and limiting miners to eight-hour workdays. "The Fourteenth Amendment does not enact Mr. Herbert Spencer's 'Social Statics.' "

The other dissent, by Justice John Marshall Harlan, put the matter less pithily but more carefully: "A legislative enactment, Federal or state, is never to be disregarded or held invalid unless it is, beyond question, plainly and palpably in excess of legislative powers." The New York statute was not a "plain, palpable invasion of rights secured by the fundamental law" because, among other things, the Fourteenth Amendment contains no "right of contract."

In 1905, conservatives, such as Justice Peckham, were the judicial activists and liberals were the defenders of strict construction. The liberal -- that is, nonactivist -- interpretation earned the praise of most commentators, almost all historians, and ultimately the support of the court's majority.

Suppose you were a United States senator who had just read the Lochner case. How should you, in 1905, evaluate presidential nominees for the court? One way would be to decide how you felt about the results of the case. Say you were opposed to state laws regulating business. You would then support justices who favored laissez-faire economics.

But what arguments would you make to other senators whose votes you wish to have in the confirmation battle? "Vote for laissez-faire economics"? A vote on results is a test of strength, not of principle. The Senate of 1905 had a Republican majority. If it followed your view that only results matter, it would back another justice like Peckham. But in time the Democrats would win control of the Senate (as in fact they did, in 1912). What arguments would you then use to dissuade uncommitted Democrats from voting for justices who would always back factory laws? If you had no argument save results, you would have to forgive the Democrats for saying, "We won, it's our turn."

Suppose instead that you were a liberal who believed in factory laws and renounced Mr. Herbert Spencer. You could not expect even a Democratic Senate to have a majority of liberals in it. What arguments would you make, to what principle would you appeal, to rally those senators who disagreed with you on factory laws and who rather liked Mr. Spencer? In a mere test of strength, with "results" the only question, it is doubtful that the Democratic-controlled Senate would have confirmed Louis Brandeis in 1916.

It was an appeal to neutral principles that carried the day for some key senators. Harlan and Holmes provided such a principle to the Senate: The states are free to exercise their police powers except when that exercise violates some plain and palpable provision of the Constitution. Whether judges like or dislike laissez-faire economics is irrelevant. Within broad limits, economic policy is to be decided by elected legislators. In states with liberal majorities, factory laws will be enacted; in those with conservative majorities, such bills will fail.

The Supreme Court is not a legislature. It is an undemocratic, even antidemocratic, branch of government. It cannot justify its claim to extraordinary constitutional powers by appealing to popular consent. It can only justify them by arguing that it explicates and enforces a nonpartisan and often unpopular principle, namely, comparing laws to the Constitution to see if the former square with the latter.

Decades ago, Prof. Herbert Wechsler of Columbia University explained the importance for judicial interpretation of neutral principles. They are not always easily discovered and they are rarely free of controversy. But by and large those principles have aided "liberal" causes far more than "conservative" ones -- witness the growing protection afforded to unpopular minorities by the steady application of the several rather clear principles enunciated in the First Amendment. If having an ideology that leads to the "right results" had always been the chief test of judicial fitness, the neutral principles on which so much of our liberal state now depends would have been suffocated by conservative majorities.

The Senate would do well to keep this in mind as it debates the nomination of Robert Bork. Currently, activists tend to be liberals, and strict constructionists to be conservatives. For liberals to make their case against Judge Bork on the grounds that he wishes to condemn women to back-alley abortions or blacks to servitude is as wrong and as shortsighted as for liberals in 1905 to have made their case against Justice Peckham on the grounds that he hated bakers. In both cases, neutral principles are visible -- namely, deference to the legislature except when plain and palpable constitutional rights are violated. The senators should explore Judge Bork's understanding of those principles in their questioning of him.

The writer is Collins professor of management and political science at UCLA.