I've got to say that I don't know who the Fashion Director was at the Dallas PD at that particular time, but I have a problem with his color coordination skills.
First, that doesn't even look like jail garb. Not really. They talk about it, and the main characteristic they want for jail garb is that it stand out as jail garb, that at first glance, anyone knows that they are looking at a person in custody, a prisoner. Often, the shirt will say "prisoner." And if it doesn't, it will be something like a bright orange jump suit, something that no one but a prisoner would wear. But, as you can see, Jack Ruby looks more like he has cabana clothes on- something suited for a cruise. "Shuffleboard, anyone? What time is the next buffet?"
But, what I don't get is: why, if you were going with white shirt and white pants, would you go with jet black socks and jet black shoes? I'm no Martha Stewart, mind you, but I'm pretty sure that's considered a clash. So, why would you do that?
And why, exactly, is it important to have the man wear jail underwear? I already gave the reason why he's in jail garb: so that he can be instantly recognized as a prisoner. The idea is that, say he were to escape, people would recognize that he was an escaped convict. But, what does that have to do with his underwear? Nothing. So, why replace it? Why require prisoners to wear your regulation underwear? Why can't they just wear their own underwear? From their standpoint, it's probably their preference, and from your standpoint, how do you benefit from putting them in different underwear? What makes it worth the trouble and expense to do that? Answer the question.