Custom (Municipal Practice)

What It Is

In Monell v. Department of Social Services, 436 U.S. 658 (1978), the Supreme Court held that municipalities can be liable under § 1983 when an unconstitutional “policy or custom” causes a constitutional violation. While a “policy” is a formal, officially adopted rule, a “custom” is something different — it’s an informal practice so widespread and persistent that it carries the force of law, even though no one officially wrote it down.

This is important because cities rarely adopt written policies that say “violate people’s rights.” The real-world harm usually comes from unofficial but deeply ingrained practices.

What You Must Show

To prove a municipal liability claim based on custom, you typically need to demonstrate:

1. A pattern of similar conduct — Not just your incident, but a history of the same type of misconduct by the municipality’s employees
2. The pattern was widespread — Isolated incidents aren’t enough. You need to show it happened frequently
3. Officials knew or should have known — The practice was so common that policymakers must have been aware of it, and their failure to stop it amounted to deliberate indifference
4. The custom caused your injury — Your specific constitutional violation was a direct result of this entrenched practice

How to Prove a Custom

Evidence of a custom can include:

• Prior complaints about similar misconduct — citizen complaints, internal affairs records
• Prior lawsuits alleging the same type of violation
• Statistical evidence — data showing a pattern (e.g., disproportionate use of force)
• Testimony from officers or officials acknowledging the practice
• Lack of discipline — officers engaged in the conduct without meaningful consequences
• Training records showing the practice was taught or tolerated

How Many Incidents Do You Need?

There’s no magic number, but a single prior incident is almost never enough. Courts want to see enough similar events to conclude that the behavior was truly a “custom” rather than a series of unconnected mistakes. The more incidents you can document, the stronger your claim.

Custom vs. Failure to Train

Custom claims are related to but different from failure to train claims. A custom claim says “this unconstitutional practice was so common it became de facto policy.” A failure-to-train claim says “the city’s training was so inadequate it was obvious violations would result.” Both can support Monell liability, but they require different evidence.

Key Cases

• Monell v. Department of Social Services, 436 U.S. 658 (1978) — Municipalities liable for unconstitutional “policies or customs”
• Adickes v. S.H. Kress & Co., 398 U.S. 144 (1970) — Early recognition that a “custom” can form the basis of § 1983 liability
• Connick v. Thompson, 563 U.S. 51 (2011) — A single incident generally insufficient to establish custom or pattern