What nonsense. Eyewitnesses are the least reliable form of evidence. Convictions can be and often are obtained solely on forensic evidence. There was a witness who saw Oswald fire the final shot but his ID of Oswald is probably the least compelling piece of evidence against Oswald. The case can be made entirely on the forensic evidence. That evidence includes finger and palm prints, fiber evidence, ballistic matching, medical evidence, film evidence, and a paper trail proving Oswald ordered and was the owner of the murder weapon. There isn't a scrap of any of the above types of evidence that indicates there was a second shooter. All the forensic evidence points to Oswald alone.
I don't know where you got your understanding of constitutional law but nowhere in the Constitution does it say eyewitness accounts are required to obtain a conviction nor does it say eyewitness accounts should be accepted at face value. I've served on four juries, two civil and two criminal. Each time the judge instructed us to weigh the credibility of the witnesses based on a number of factors. I was on a murder trial where we had both eyewitness and forensic evidence. The only disagreement among the jurors was whether the element of premeditation had been proven. I was one of two who believed it had not and we prevailed. We convicted the accused of the lesser charge. I also sat on a trial in a check forgery case. The prosecution presented no eyewitnesses to the crime yet the forensic evidence was so convincing we convicted the guy in less than an hour. Eyewitnesses are not end all, be all nor should they be.
Correction. They saw SMOKE. Modern gun smoke does not billow. It dissipates almost immediately and if it had been fired from behind the fence, it wouldn't have made it into the clear for anybody on the overpass to see it. Lots of people had different ideas about where the sounds indicated the shots came from. Some said all three shots came from the GK and some said all three came from the direction of the TSBD. The three spent shells in the sniper's nest tells us which group got it right.
It's not called eye witness accounts in legalese terms for the simple reason human beings have five senses not just sight. It is termed witness to the fact which must be first hand for it to be credible. For example Nell and John Connally in their testimony stated that they did not see the shot which blew apart Jack kennedy's head but both said they heard it and felt it. By that they meant they heard the impact and felt the blood and brain tissue hit their bodies. Two people of sound mind and impeccable integrity, that's as good as you'll get from inside the limo. They also stated that the shot that hit Kennedy in the neck was two seconds before the one that hit John Connally. They never changed their story - ever.
You cannot cherry pick the statements of the Connally's just because Arlen Specter came up with the notion that it was a single bullet that hit both Kennedy and Connally. At some point in this assassination you have to start believing people who were in the limo not some dude in a suit making up strange bullet theories.
In my previous post I called Brennan a liar. The reason being, it is impossible for a witness to see the height of a gunman through a brick wall and boxes and his build, whether he's nice looking or not and how much he weighs yet the Dallas police acted on it and the Warren commission believed it too. The same commission then ignored two statements from high status witnesses who were actually in the limo!!!!!
When does common sense prevail? When does this nonsense stop?