---
title: "Lochner Era | Constitutional Law I"
description: "Lochner Era is the period when the Supreme Court used substantive due process to strike down economic and labor laws, limiting state police power."
canonical: "https://fiveable.me/constitutional-law-i/key-terms/lochner-era"
type: "key-term"
subject: "Constitutional Law I"
unit: "Unit 4"
---

# Lochner Era | Constitutional Law I

## Definition

The Lochner Era is the period when the Supreme Court, especially in Lochner v. New York, used substantive due process to strike down labor and economic regulations. In Constitutional Law I, it shows the Court's early protection of economic liberty over state regulation.

## What It Is

The Lochner Era is the name for a stretch of Constitutional Law I doctrine, roughly from the late 1800s to the 1930s, when the Supreme Court often struck down economic and labor regulations. The Court treated freedom of contract and economic liberty as constitutionally protected interests, especially when states tried to regulate wages, hours, or working conditions.

The era gets its name from Lochner v. New York (1905), where the Court invalidated a New York law limiting bakery workers' hours. The Court said the law interfered too much with the employer's and employee's right to make their own contract. That sounds neutral on paper, but in practice it meant judges were deciding when a labor law crossed the constitutional line.

The legal tool behind this period was substantive due process. Instead of only asking whether a state followed fair procedure, the Court asked whether the law itself was too intrusive. During the Lochner Era, that doctrine was used to protect economic choices from state control, even when legislatures were trying to address unsafe factories, long shifts, low pay, or exploitative bargaining conditions.

The state usually defended these laws under its police power, which is the authority to protect health, safety, morals, and general welfare. The Lochner Court often treated that power narrowly. If a regulation looked like a direct labor protection rather than a true health or safety rule, the Court was more likely to strike it down.

A good way to spot the Lochner Era in class is to ask: who gets the benefit of constitutional protection here, and what kind of regulation is being limited? If the case is about hours, wages, or workplace rules, and the Court is suspicious of the law because it burdens economic liberty, you are probably in Lochner territory. The era faded in the 1930s as the Court became more willing to uphold government regulation, especially in response to the New Deal.

## Why It Matters

The Lochner Era matters because it shows how constitutional interpretation can change the balance between markets and government. In Constitutional Law I, it is one of the clearest examples of the Court using the Due Process Clause to protect economic rights, even when elected lawmakers wanted to regulate working conditions.

That makes it useful for reading later cases and doctrines. Once you know the Lochner Era, you can see why courts and professors talk so much about judicial restraint, economic liberty, and the limits of substantive due process. The era also sets up the shift toward broader acceptance of regulation, which matters when the class moves into New Deal cases and modern Commerce Clause analysis.

It also gives you a clean way to compare legal arguments. A law about bakery hours, minimum wages, or workplace safety can be framed as a health measure under police power or as an unconstitutional interference with contract freedom. Lochner Era cases show how much turns on the Court's view of purpose, evidence, and the level of deference given to legislatures.

## Connections

### [Substantive Due Process](/constitutional-law-i/key-terms/substantive-due-process)

This is the doctrine the Lochner Court relied on to protect economic liberty. Instead of just checking whether the state used fair procedures, the Court asked whether the law itself violated a protected liberty interest. In Lochner Era cases, that liberty interest often meant freedom of contract, which let the Court strike down labor regulations it saw as too intrusive.

### Police Power

States defended wage and hour laws by saying they were exercising police power to protect health and safety. The Lochner Era is partly a story about the Court narrowing that power when the regulation looked economic rather than safety-based. If you are comparing the two, ask whether the law is framed as public welfare regulation or as interference with private agreement.

### Muller v. Oregon

Muller is often discussed alongside Lochner because it upheld a labor regulation, showing that the Court was not uniformly anti-regulation. It approved a maximum-hours law for women, which shows how the era could tolerate some labor limits when the Court thought special health or social concerns justified them. That tension is useful for seeing that Lochner Era doctrine was not perfectly stable.

### [Rational Basis Review](/constitutional-law-i/key-terms/rational-basis-review)

Modern courts usually defer to legislatures on economic regulation, which is the opposite of the Lochner-era approach. Under rational basis review, a law will usually stand if the government can point to a legitimate purpose. Comparing that standard with Lochner helps you see how constitutional law shifted from active policing of economic laws to much greater judicial restraint.

## On the AP Exam

A case brief, issue spotter, or short essay question may ask you to identify why a labor law was struck down and what doctrine the Court used. Your job is to connect the facts to substantive due process, explain that the Court treated economic liberty as protected, and distinguish that approach from modern deference to state regulation.

If a prompt gives you a law limiting work hours, minimum pay, or contract terms, ask whether the answer should be Lochner-style skepticism or police power deference. You can also use the term to compare two eras of doctrine: before the 1930s, the Court often policed economic legislation more aggressively; later, it usually let legislatures regulate unless there was a stronger constitutional problem. In discussion or essays, that historical shift is often the whole point.

## Key Takeaways

- The Lochner Era is the period when the Supreme Court often struck down labor and economic regulations to protect economic liberty.
- Lochner v. New York is the signature case, and it involved a state law limiting bakery workers' hours.
- The doctrine behind the era was substantive due process, especially the idea that freedom of contract deserved constitutional protection.
- States defended labor laws through police power, but the Court often treated that power narrowly during this period.
- The era ended as the Court became more willing to uphold economic regulation, especially during the New Deal.

## FAQs

### What is the Lochner Era in Constitutional Law I?

The Lochner Era is the period when the Supreme Court often used substantive due process to strike down laws regulating wages, hours, and working conditions. It is named after Lochner v. New York, the bakery-hours case. In class, it usually comes up as the Court's most famous pro-economic-liberty period.

### Why did the Court strike down labor laws during the Lochner Era?

The Court thought many of those laws interfered with freedom of contract and individual economic liberty. It was skeptical that every labor rule was a real health or safety measure, so it often refused to defer to state lawmakers. That made the era a major example of judicial resistance to regulation.

### Is the Lochner Era the same thing as substantive due process?

Not exactly. Substantive due process is the broader doctrine, while the Lochner Era is a historical period when the Court used that doctrine in a particularly aggressive way to protect economic rights. So substantive due process is the tool, and the Lochner Era is the time when that tool was used most famously against labor regulation.

### How does the Lochner Era show up in exam or essay questions?

You may get a fact pattern about a state law limiting work hours, wages, or business contracts and need to explain whether the Court would uphold it. A strong answer connects the law to substantive due process, police power, and the Court's old habit of protecting economic liberty. It is also a good comparison point for modern deference to regulation.

## Related Study Guides

- [4.2 Substantial Effects Test and Aggregation Principle](/constitutional-law-i/unit-4/substantial-effects-test-aggregation-principle/study-guide/0mf0b8XASOUjNdOc)

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