This is J. Michael Flanagan, the defense attorney for Dr. Conrad Murray. Murray is on trial for involuntary manslaughter in the death of Michael Jackson. Flanagan is a skilled and experienced attorney, but in many cases, I would disagree with his gesture of pointing at a witness (in this case Dr. Thao Nguyen, Cardiologist). In particular, I would steer him away from pointing with his index finger (forefinger). While this body language may certainly make the witness squirm and feel uncomfortable - and this may work to his advantage, he should weigh this against how the jury may feel. Pointing is considered a significant insult in nearly every culture and country around the World. If any jury member has empathy for the witness being questioned, she/he will feel as if they are being pointed at, chastised, and thus falsely persecuted along with the witness. Got empathy? Your jury does.
A better way to point would be with the whole hand, palm up. The fingers and arm should both be extended (but not fully extended, some flexing to the shoulder, elbow and fingers should be displayed) but relaxed.