The long-awaited trial of two Albany, N.Y., Muslims snared in a money laundering-for-terrorism sting got under way Wednesday in federal court, where the legal and moral connotations of entrapment were a persistent undercurrent.

In his introductory charge, Senior Northern District Judge Thomas J. McAvoy instructed the jury that prosecutors must prove as a legal matter that Mohammed M. Hossain and Yassin M. Aref were predisposed to commit the crimes they were afforded an opportunity to commit by the government — a burden Assistant U.S. Attorney William C. Pericek readily embraced in his opening.