While there is no surefire on-the-spot way to sniff out dissemblers, there are some helpful tactics for uncovering untruths.
Liars often give short or one-word responses to questions, while truth tellers are more likely to flesh out their answers. According to a 2003 study by DePaulo, a liar provides fewer details and uses fewer words than an honest person, and talks for a smaller percentage of the conversation.
Skilled liars don't break a sweat, but the rest of us get a little fidgety. Four possible giveaways: shifty eyes, higher vocal pitch, perspiration and heavier breathing. Of course, not everyone who doesn't meet your gaze is a liar.
If you think this advice might be helpful to your deposition-and-trial practice, check out the full article. While not written specifically for lawyers, much of it applies to what trial lawyers do.