1. the person is not qualified to have an expert opinion on the subject,
2. experts in the field disagree on this issue.
3. the authority was making a joke, drunk, or otherwise not being serious
Satisfying, or pointing out in argument the satisfaction of, one of these conditions is referred to as "subverted authority". I used it in pointing out that Gordon Wood is an author of markedly antirepublican and antidemocratic views who considers the American Revolution a failure and Hamilton as some sort of demiurge. You used it in dishing up the speckled career and deep-pink sympathies of Jack Rakove, and his lack of credentials in the field in which he was writing.
When confronted with the erudition of Justice Scalia, the first thing Professor Wood did was note his lack of credentials for legal argument.
You must not have read very much of his work. Otherwise you wouldn't make such an ignorant statement.