The most comforting sentence in a courtroom is “everybody does it this way.” It is also, sometimes, a confession.
Custom is what an industry actually does. The defense reaches for it as a shield in every case: our crew followed standard practice, our dispatcher did what every dispatcher does, this is how the whole trade has always operated. Custom feels like safety in numbers, and juries feel the pull of it too.
But custom is only evidence of the standard of care. It is not the standard itself.
That distinction is the entire fight, and the law settled it almost a century ago. A fleet of tugboats went to sea without radios because no tugboat carried radios. When a tow was lost in a storm the radios would have warned them about, the owners pointed to custom: nobody had them. The court was not moved. A whole industry, it held, can lag behind what reasonable care plainly requires, and courts will not let an entire trade set its own low bar and call it safe. Custom is a witness. It is not the judge.
That cuts both ways, which is what makes the word useful.
As a sword, custom is devastating. When the defendant’s own trade association publishes a practice and the defendant ignored it, custom stops being a shield and becomes the yardstick they failed to meet. Now the standard is not your opinion of careful. It is theirs, in their own manual, unmet.
The move: pull the industry standards early. The trade manuals, the association guidance, the published safety practices. Then set two facts side by side. What the industry says it does. What this defendant actually did. The gap between them is the case.
The other edge. Do not let the defense hide a shortcut behind the word custom, and do not overreach by dressing one company’s bad habit up as the whole industry’s rule. Precision protects you. Reaching gets you caught.
One word. Custom tells you what is usual. It does not tell you what is safe, and a jury is allowed to know the difference.
The tugboat case is The T.J. Hooper, 60 F.2d 737 (2d Cir. 1932). Read the opinion.
