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Insane
Also written: Insanity
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At a glance
Source-by-source
“In U.S. criminal law, insanity is a legal question, not a medical one. … Use the term "mental illness" instead of "insane" or "mentally deranged," except in a quote or when referring to a criminal defense.”
NCDJ — the chapter's anchor source — treats "insane," "insanity," and "mentally deranged" as informal, potentially offensive stand-ins for mental illness, advising "mental illness" instead — with two exceptions: a quote, or the legal sense, since in U.S. criminal law insanity is a legal rather than medical question.
“The most common example is the pervasive use of the word "crazy" or "insane" as a pejorative. … it can be exhausting to hear a medical issue be used as shorthand for every piece of bad news.”
Sierra Club names the pejorative use of "insane" (paired with "crazy") as the most common form of unconscious ableism, noting how exhausting it is for people with mental-health challenges to hear a medical issue used as shorthand for bad news, and directs writers toward more specific words.
“Term to avoid: insane. Suggested alternative: person with a preexisting behavioral health disorder.”
APA's term-to-avoid table lists "insane" (alongside "crazy" and "mental defect"), prescribing person-first phrasing such as "person with a preexisting behavioral health disorder" instead.
“The terms insane, insanity and mentally deranged are commonly used informally to denote mental instability or mental illness but can be considered offensive. … Use mental illness or mental disorder instead of insane or mentally deranged, except in a quote or when referring to a criminal defense.”
The Diversity Style Guide treats "insane," "insanity," and "mentally deranged" as informal and potentially offensive terms for mental instability, preferring "mental illness" or "mental disorder," and — echoing NCDJ — preserves the exceptions for quotes and the legal criminal-defense sense.
Synthesis
“Insane” follows the same rule as “crazy,” with one difference: it is also a legal term. NCDJ (the chapter’s anchor), the Diversity Style Guide, and APA all treat “insane,” “insanity,” and “mentally deranged” as informal, now-offensive stand-ins for mental illness, preferring “mental illness” or “mental disorder” (APA: “person with a … behavioral health disorder”). Sierra Club pairs “insane” with “crazy” as the most common everyday ableism, a medical issue used as shorthand for bad news.
The difference is legal. In U.S. criminal law, insanity is a legal question, not a medical diagnosis, so NCDJ and the Diversity Style Guide both carve out an exception: use “mental illness” instead of “insane,” except in a quote or when referring to a criminal defense (the insanity defense; found not guilty by reason of insanity). That exception is what separates this page from crazy, which has no comparable technical sense.
The guidance is stable across the 2021–2023 sources. This page pairs with mental illness, mental health, and crazy.
Audience notes
- Journalists and editors. Replace “insane” with “mental illness” or “mental disorder” in your own voice. Keep it only for the legal sense — “the insanity defense,” “found not guilty by reason of insanity” — or inside an essential quote.
- Advocates and internal comms. As with “crazy,” the usual slip is the casual intensifier (“this is insane”). Name the specific thing instead.
- Watch the legal context. When writing about a court case, “insanity” may be the accurate legal term — that is the one place it stays.
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