After three decades as a defense attorney, Robert Simels took the stand himself for the first time yesterday, in order to defend against charges that he plotted with his client, the since-convicted Guyanese drug kingpin Shaheed Khan, to threaten and bribe potential witnesses.

Throughout the week-and-a-half-long trial, Mr. Simels’ defense has centered on the idea that an attorney must go to extraordinary lengths to investigate a client’s case­, even when it means—as in the present case—pretending to agree with one witness to terrorize others, in the hope of maintaining the relationship or developing new leads.