Last week, I had a few hours of enforced idleness (which I thought, at the time, would stretch into a day or so), so, casting about for reading material on my Kindle, I came across Chesterton's Eugenics and Other Evils.
I didn't get all that far into it before my reading time was interrupted, but wow.
In a nutshell:
It only extends the principles of the Lunacy Laws to persons without a trace of lunacy.
When you hear calls for limiting or abolishing due process, or restricting the rights of people who are arguably a little off-kilter (or merely out of line with the fashionable beliefs of the moment) but are not certifiably insane... it's the same destructive nonsense against which Chesterton was arguing back in 1922 (or, actually, earlier).
Chesterton notes that the principles of law do need certain exceptions... but that those exceptions do need to be exceptional, and must not be expanded to become the norm. Madmen are dealt with outside the normal legal processes because they are madmen, and do not (and cannot) share our common frame of reference.
For this reason, and for this alone, the lunatic is outside public law. This is the abysmal difference between him and the criminal. The criminal admits the facts, and therefore permits us to appeal to the facts. We can so arrange the facts around him that he may really understand that agreement is in his own interests. We can say to him, "Do not steal apples from this tree, or we will hang you on that tree." But if the man really thinks one tree is a Lamp-post and the other tree a Trafalgar Square fountain, we simply cannot treat with him at all. It is obviously useless to say, "Do not steal apples from this lamp-post, or I will hang you on that fountain." If a man denies the facts, there is no answer but to lock him up. He cannot speak our language: not that varying verbal language which often misses fire even with us, but that enormous alphabet of sun and moon and green grass and blue sky in which alone we meet, and by which alone we can signal to each other. That unique man of genius, George Macdonald, described in one of his weird stories two systems of space co-incident; so that where I knew there was a piano standing in a drawing-room you knew there was a rose-bush growing in a garden. Something of this sort is in small or great affairs the matter with the madman. He cannot have a vote, because he is the citizen of another country. He is a foreigner. Nay, he is an invader and an enemy; for the city he lives in has been super-imposed on ours.
The notion of State-enforced eugenics is just one of a complex web of related evils, involving loss of the rule of law and the denial of the individual.
(And, remember: the evil Eugenist Prussian menace, when the book was begun, was the Kaiser. Hitler wasn't even on the yet-to-be-invented RADAR.)
Available for free in various places, such as here.
Read it. Everyone should read it. It is at least as relevant today as when it was written.