dumptruck, n.² — Green’s Dictionary of Slang

dumptruck n.²

[? one can dump v. (1) all one’s troubles on them or their incompetence dumps one in jail]

(US Und.) a public defender; also attrib.

1977		E. Bunker Animal Factory 5: ‘Fuckin’ dump-truck P.D.’s,’ muttered the Chicano.
1992		Bentley & Corbett Prison Sl. 20: Dumptruck An attorney, usually a public defender. Because of the huge caseloads and the high number of plea agreements, inmates feel they are being sentenced by the truck load. (Archaic: tongue, warbler).
2000		Other Side of the Wall: Prisoner’s Dict. July 🌐 Dump Truck: A lawyer who makes an easy deal at the expense of the client.