Green’s Dictionary of Slang

prostitution; thus sacking law n., such an occupation.

1552		G. Walker Detection of Vyle and Detestable Use of Dice Play 18: Thus they give their own conveyance the name of cheating law; so do they other terms, as sacking law, high law, figging law, and such like [...] Sacking law signifies whoredom.
1591		Greene Notable Discovery of Coosnage in Grosart (1881–3) X 37: The Art of Cony-catching. These are the eight lawes of villanie leading the high waie to infamie. [...] In Sacking Law. The Bawd if it be a woman, a Pander The Bawd, if a man, an Apple squire The whoore, a Commoditie The whoore house, a Trugging place.
1592		Greene Disputation Betweene a Hee and a Shee Conny-Catcher (1923) 11: To thincke that your faire lookes can get as much as our nimble fingers, or that your sacking can gaine as much as our foysting.
1608		Dekker Belman of London (3rd) G4: The Trade of these Tale-bearers goes vnder the name of the Sacking-law. [...] Rightly may it be called sacking.