Hello, I’m Zhan Qingyun.

The Clayton Act of 1914 has been called the ‘Magna Carta of American labor,’ echoing the famous English charter that constrained royal power.

That name reflects its historic importance, especially because antitrust law had previously been used so widely against unions.

Yet the Clayton Act merely stopped courts from applying antitrust law to restrict strikes and collective action. It could not prevent hostile local governments and courts from suppressing labor by other means.

As late as Coppage v. Kansas (1915), the Supreme Court said the Constitution protected an employer’s freedom to contract with an employee on the condition that the employee not join a union. Today, freedom of association is understood to protect union membership. The Court then reasoned in reverse: employers had liberty too and could require a promise not to unionize before offering continued employment.

When did that truly change? Only when society ceased to function and systemic reform became unavoidable—during the Great Depression and Franklin Roosevelt’s New Deal.

In the 1930s the Roosevelt administration introduced measures protecting labor rights, improving conditions and welfare, and establishing minimum wages. It overturned a long policy of limited government and nonintervention. The New Deal also protected workers’ rights to join unions, bargain collectively, strike, act together, and support one another.

Legislation affirmatively defined those rights. The Clayton Act had told courts what they could not do with antitrust law, but had not said which union rights the law protected. New statutes now listed them.

The episode shows that although judges and precedent strongly shape American law, legislators can at any time overturn judicial rulings, establish a new starting point and basic principles, and leave courts to develop the law from there.

The National Labor Relations Act of 1935 protected not only individual workers but labor organizations—that is, unions—as institutions.

American unions then expanded rapidly.

From the 1930s through the 1950s, unions grew into enormous interest groups. Workers could organize a small plant-level union, but usually affiliated with stronger federations. Unions and major corporations became powerful adversaries, repeatedly fighting in court to define the limits of each side’s rights.