By Clayton T. Robertson (Criminal Defense / Civil Litigation Attorney)
As you can tell by my prior posts, I'm a huge proponent of the investigation component of a criminal defense practice. This typically appeals to clients who are either innocent or who have been overcharged, as is so often the case. It doesn't work as well if you're guilty as charged. In that case, less is often more. (Of course, there are exceptions to all of this, which is one reason you need to consult with an attorney. Both approaches can be used successfully depending on the particular case.)
A significant component of an investigation are witness interviews. In turn, a significant component of witness interviews is not only what is said, but how it is said and the manner in which it is said. This includes the speaker's tone and body language, among other issues. We can rely upon our skilled investigators for their work-product assessments of a witness's demeanor and credibility, though these attributes can be evaluated in other ways as well. Moreover, at trial, when these persons potentially testify, your attorney will be able to further question them under the scrutiny of cross examination (if they are adverse witnesses). Body language plays a significant role, including to a jury. If they are "friendly witnesses," we can assess their helpfulness to your case before trial and decide whether to call them as a witness. In all areas of a criminal defense practice, as in life, we are evaluating people by both their verbal and non-verbal cues.
Reading someone's body language is both art and science. I have studied books that systematically collect the classic "tells" of body language (i.e., those universal mannerisms that can generally be interpreted in a particular way, often across cultures). On the other hand, every person is different in some ways, which is why the best books on the subject allow for "idiosyncratic" variations across individuals. The way to solve this conundrum is to "baseline" a person from prior interactions (or earlier parts of the same interaction). You identify their "normal" behaviors when they are telling the truth on unthreatening subjects on which you know they likely are telling the truth (such as mundane everyday events or basic biographic details), then identify deviations in their body language on subjects in which the truth-telling function is potentially most strained (which is the true focus of the questioning). That said, reading a person's body language is also part "art." Some people are better at it than others by nature. Details are important. And to find details, you need to be naturally observant. You can train this trait to some extent, but not completely.
I can (and probably will) write numerous blogs on this topic. The purpose of this blog is to introduce you to two books written by a former FBI special agent who is well known for his ability to read people. His name is Joe Navarro. Navarro apparently was so good he became a master "spycatcher," a "human lie detector," and an instructor at the FBI. The two books he has authored are listed below. Read and use these books in your personal and professional lives. And, lastly, hire a criminal defense attorney who is aware of these techniques and knows by instinct how to apply them, including at trial.
For a blog post by me on a related subject, see here ("The Psychic Investigator"):