This proverb is used when someone has been accused of behaving badly in the past, with the result that people now expect them to behave the same way in the future, whatever the actual facts of the case turn out to be. Once the label is attached, it sticks: the person’s past is treated as proof of their present guilt, and nothing they do afterwards is judged on its own merits. It is most often said sympathetically, about someone who feels they can never escape an old mistake or an unfair accusation, no matter how they have changed or how weak the original evidence was.
What’s the origin of the phrase ‘give a dog a bad name and hang him’?
The saying grows out of much older material about reputation rather than out of any specific story about a dog. The word “name” had already been used to mean a person’s reputation, as in a “bad name” or “ill name”, from about 1400 onward. Long before the dog version existed, English proverb collections were circulating a close relative of it: “He that hath a ill name is half hanged” appeared repeatedly in proverb collections from 1546 onward. That line makes the logic explicit. A ruined reputation does half the work of a conviction, because suspicion alone is often enough to condemn someone, just as a dog thought to be dangerous or diseased might be destroyed on reputation alone rather than on anything it had actually done.
The dog wording itself is on record by the early eighteenth century, when James Kelly included a version of it in his 1721 collection of Scottish proverbs. That later form, with “dog” substituted for the more abstract idea of a person’s name, turns that old proverb into something more vivid and more quotable, pairing the unfairness of reputation with the unforgiving finality of a hanging. The dog stands in for anyone whose character has been fixed in other people’s minds, and the hanging stands for the harsh, irreversible way such judgements are often acted on. It sits close in spirit to being in someone’s bad books, though it goes much further: that phrase describes temporary disapproval, while this one describes a reputation treated as a life sentence.