Green’s Dictionary of Slang

shyster n.

also shice, shise, shuyster, shyster lawyer
[Ger. Scheisser, shitter or Du. scheidsman or schiedsreichter, an arbitrator, an umpire. Alternatively, f. a New York lawyer named Scheuster (pron. shyster), whose courtroom antics so infuriated Justice Osborne of the city’s Essex Market Court that he began talking of ‘scheuster’ practices; for full discussion see Quinion, World Wide Words (2004)]

1. [mid-19C+] (orig. US) a lawyer, usu. a crooked one, or with the implication that any lawyer is innately untrustworthy .

2. [mid-19C+] a general term of abuse, the assumption being one who cheats.

3. [1920s–30s] a crooked business man.

4. attrib. use of sense 3.

5. [1930s] (UK Und.) one who refuses to pay their debts.

6. see shicer n. (5)