What makes a trial lawyer trustworthy? The keys to trial persuasion are sincerity sincere and the ability to project that sincerity. Sincerity, more than eloquence, a good appearance or any other attribute, is what really matters in trial advocacy.

Sincerity in the trial context means that the lawyer believes the cause is just. It is helpful to look to how Abraham Lincoln as a trial lawyer approached trial work. The first Lincoln lesson is contained in his creed: “I must stand by anyone that stands right. Stand with him while he is right, and part with him when he goes wrong.” A trial lawyer must have a sincere belief in the justness of the cause.
This second Lincoln lesson continues to explore that theme – sincerity – and the second lesson is that the trial lawyer must project the sincerity to the audience.

While a trial lawyer can never state a personal opinion to a jury about the justness of the cause because that violates the rules of professional conduct, no prohibition exists that bars a lawyer from being sincere about the cause. Sincerity is the quality that makes for a great communicator in trial. You are your case. If you are sincere and can project that to the jurors, you will be able to effectively convey your case to them.
Recognizing that above all else sincerity matters when it comes to communication, here is a newspaper reporter’s account of what he observed at Lincoln’s Cooper Union speech, which is the subject of Harold Holzer’s book Lincoln at Cooper Union: The Speech that Made Abraham Lincoln President, Simon and Schuster (2004):
“When Lincoln rose to speak, I was greatly disappointed. He was tall, tall, oh, so tall, and so angular and awkward that I had for an instant a feeling of pity for so ungainly a man . . . His clothes were black and ill-fitting, badly wrinkled – as if they had been jammed carelessly into a small trunk. His bushy head, with the stiff black hair thrown back, was balanced on a long and lean head-stalk, and when he raised his hands in opening gesture, I noticed that they were very large. He began in a low tone of voice – as if he were used to speaking out-doors and was afraid of speaking too loud.
“He said, ‘Mr. Cheerman,’ instead of ‘Mr. Chairman,’ and employed many other words with an old-fashioned pronunciation. I said to myself, ‘Old fellow, you won’t do; it is all very well for the Wild West, but this will never go down in New York.’ But pretty soon he began to get into the subject; he straightened up, made regular and graceful gestures; his face lighted as with an inward fire; the whole man was transfigured.
“I forgot the clothing, his personal appearance, and his individual peculiarities. Presently, forgetting myself; I was on my feet with the rest . . . cheering the wonderful man. In the closing parts of his argument you could hear the gentle sizzling of the gas burners.”
Lincoln’s sincerity and conviction came across in his Cooper Union address and swayed the audience. Public speaking research suggests that two things emerge as the most powerful in persuasion: sincerity and conviction of the speaker. And, this explains why Lincoln had this effect on his audience.