Green’s Dictionary of Slang

1. a pickpocket [the dependence on sleight of hand].

1610

Jonson Alchemist I i: Cow-herd. Conjuror. Cutpurse. Witch. O me!

2. (UK Und.) a trial judge; go before the conjuror, to be tried at the assize [what he ‘pulls out of his hat’ is a sentence].

1785		Grose Classical Dict. of the Vulgar Tongue n.p.: Fortune teller, or cunning man, a judge, who tells every prisoner his fortune, lot, or doom; to go before the fortune teller, lambskin man, or conjuror, to be tried at an assize.
1796		Grose Classical Dict. of the Vulgar Tongue (3rd edn).
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.