And the problem of good intentions.  From a review of a new biography of Louis Brandeis. In the Lochner decision:

As Justice Rufus Peckham wrote for the majority, while New York certainly possessed the power to enact health and safety regulations (as all good progressives wanted), the maximum hours provision of the Bakeshop Act "is not, within any fair meaning of the term, a health law." Not only was the baking trade "not dangerous in any degree to morals, or in any real and substantial degree to the health of the employee," but the limit on working hours involved "neither the safety, the morals, nor the welfare, of the public."

So what was the purpose of the law? As George Mason University legal historian David Bernstein has shown, the origins of the Bakeshop Act lie in an economic conflict between unionized New York bakers, who labored in large shops and lobbied for the law, and their nonunionized, mostly immigrant competitors, who tended to work longer hours in small, old-fashioned bakeries. As Bernstein observed, "a ten-hour day law would not only aid those unionized workers who had not successfully demanded that their hours be reduced, but would also help reduce competition from nonunionized workers." So Lochner not only protected a fundamental economic right, it thwarted an act of economic protectionism as well.

Something similar happened in Adkins v. Children's Hospital, where the Court struck down the District of Columbia's minimum wage law for women as a violation of liberty of contract. This was the case where Urofsky claimed Sutherland exhibited "a complete disregard for the real world." Well, here are some facts about that world. One of the figures in the case was an elevator operator named Willie Lyons, who had earned $35 per month from the Congress Hotel. Under the new minimum wage law, the hotel would have had to pay her $71.50 per month. So they fired Lyons and replaced her with a man willing to work at her old wage. That's why she sued. As the legal scholar Hadley Arkes memorably put it, "the law, in its liberal tenderness, in its concern to protect women, had brought about a situation in which women were being replaced, in their jobs, by men."