How do you know when a lawyer is lying?
His lips move.
Lawyers are known as liars, and Manhattan District Attorney Cyrus Vance Jr. has commissioned a study to get to the bottom of it as reported by Jacob Gershman for The Wall Street Journal: "more than a thousand judges and lawyers have been asked to fill out a confidential online survey seeking their help 'in assessing the prevalence, significance, and effect of perjury and false statements in the New York County civil justice system.'"
To ask the question is to know the answer.
Further reading that may be of interest: