Origin of the term "Shyster"
Origin of the term "Shyster"--supplementary information
I've contributed to the discussion with several historical citations of "shyster" in the 1800s. They were published in Cohen's series, Studies in Slang.
The term began in New York City and was first cited in an 1843 publication by Mike Walsh called The Subterranean. "Shyster" became popular around the Tombs (as New York's famous prison was then named). "Shyster" was applied as a term of derision for non-lawyers and then for lawyers.
Cohen demonstrated that "shyster" does not come from anyone named "Scheuster." It most likely comes from the German word "scheisse" (shit, excrement).
I have an 1870s citation claiming a Chicago coinage of the term. We will find out more about "shyster" later this year, as newspapers (specifically, the Chicago Tribune and the Early American Newspapers series) become digitized. This entry will be revised as necessary.
The connection of "shyster" and New York's "Tombs" is very well documented, although not currently accessible on the web.
* * *