<p>The police have no reason to test people for intoxication, drugs, etc. Why would they help the defense? The police are just the arresting people, not the determiners of guilt. They generally test if they arrest you for something related to intoxication, not to help you get off with a diminished capacity defense. </p>
<p>As to mental illness, the appearance so far makes this really unlikely. Despite the popular culture ideas about “insanity”, in nearly every state it’s really hard to get off. Florida uses one of the toughest rules: the M’Naghten Rule, which says to be insane you either are so deranged you don’t know the nature of your actions or so deranged you don’t know what you’re doing is wrong. M’Naghten tried to kill Robert Peel - British PM in the 19thC - because he thought Peel was trying to kill him. He actually killed Peel’s secretary. He was judged psychotic - duh - but there was outrage because he was obviously trying to kill, no matter how nuts he was. So they made rules in response. I copied this next bit to show the two most famous examples of the rules: </p>
<ol>
<li>The defendant cuts a woman’s throat under the delusion that he is cutting a loaf of bread. Doesn’t know what he’s doing.</li>
<li>The defendant chops off a sleeping man’s head because he has the deluded idea that it would be great fun to see the man looking for it when he wakes up. Doesn’t understand what he’s doing. </li>
</ol>
<p>The shooter in this case knew what he was doing. That’s not in dispute: he pulled out a gun and shot (and then the gun jammed). He was arrested sitting down with the gun in his hand, which indicates he didn’t, for example, think he could shoot the victim and the victim would then jump around laughing. I see no way he could be “insane” under M’Naghten Rules. </p>
<p>I believe FL has to show sanity - not every state requires that - but it’s essentially presumed from actions so the burden is really light.</p>
<p>The only way I can think of a use for “diminished capacity” due to a condition would be if it affected his ability to reason and thus his rationality. That is a tough one. Imagine that you get angry really easy - and you inherited that anger and, to make it compelling, say your dad beat you and that day someone stole your dog. So some guy is texting at the table behind you and you lose it and strangle him or stick a fork in his neck or stab him through the heart with your steak knife. Let him off? This was the trend once upon a time when model legal codes talked “the product of a mental condition” and defense lawyers started to argue that growing up poor and unloved eliminated responsibility for crimes. Or in other words, imagine the defendant is a poor minority with a drug addict mother, an absent father, a brother in a gang, etc. and then think how many of these guys are in prisons now. </p>
<p>Or imagine you’re attacked by some guy with a sword. He kills your spouse. Cuts off your spouse’s head while shouting Allah. It’s a deranged act. You think he should go free? (I doubt it.) This is why insanity rules matter: did he know he was attacking you? (Yes.) Did he know he was killing? (Yes.) So he’s not insane. </p>
<p>But let’s say the guy has some elements of dementia. Take away the attributes that make him sympathetic - turn him into a minority, for example - and think about whether he should be let off or if you should consider his condition as maybe a factor in sentencing. And then remember everything cuts both ways. We often sentence people to long terms because we decide they’re depraved instead of abused by their tragic circumstances. So isn’t a former cop, a former captain, a former ranking officer exactly the kind of person trained to keep cool whose behavior deserves more, not less punishment? Isn’t he exactly the kind of person who most knows what is wrong? Compare him to a kid from an awful family who grew up surrounded by crime: isn’t he less likely to understand what his actions mean? Prisons are full of these people. These are the kind of arguments you have in Criminal Law class.</p>