What is "sus law"

n. (context UK informal English) A law that permitted a police officer to stop, search and potentially arrest people on suspicion of being in breach of section 4 of the (w: Vagrancy Act 1824).

In England and Wales, the sus law (from "suspected person", see below) was the informal name for a stop and search law that permitted a police officer to stop, search and potentially arrest people on suspicion of them being in breach of section 4 of the Vagrancy Act 1824.