Green’s Dictionary of Slang

high lawyer n.

a highwayman.

1592		Greene Blacke Bookes Messenger 13: I came to the credite of a high Lawyer, and with my sword freebooted abroad in the country like a Cauelier on horsebacke.
1600		J. Day Blind Beggar of Bednall-Green Act I: He wo’d be your prigger, your prancer, your high-lawyer.
1608		Dekker Belman of London G4: The theefe that commits the Robbery, and is chiefe Clearke to Saint Nicholas, is called the High Lawyer.
1610		Rowlands Martin Mark-all 50: Such as robbe on horse-backe were called high lawyers.
1625		A very pleasant nevv ditty [ballad] The high-lawyer brauely goes / on high-wayes taking rent: / But often he pawnes his cloths, /his money being spent.
1641		Brothers of the Blade 3: Serj. Faith, if all strings faile in the bow of my expectation, ile fall to my old trade, turne high-way Lawyer, or Padman.
1659		J. Day The blind-beggar of Bednal-green n.p.: Can. [H]e wo’d be your prigger, your prancer, your high-lawyer, your— Had. Your nipper, your foyst, your rogue, your cheat, your pander, your any vild thing.