I’m no expert here and have not thought about this extensively, so I have no strong opinion here. That said, at first glance:
* It seems reasonable that courts need some power to compel people to cooperate with investigations — otherwise they’d be unable to act on certain kinds of crimes, conspiracies, etc.
* What alternate justice system would you suggest specifically, which is presumably more fair and effective that this one?
As for acting on certain kinds of crimes, the job of prosecutors is to gather evidence, and find people willing to testify, to support their case. They already do this, sometimes offering things in exchange for testimony (such as immunity for their part in the crime), to get witnesses to cooperate and offer testimony that can be believed. If they can't get someone to voluntarily testify, however, it seems counterproductive to me to toss them in jail to punish them for not cooperating; from the outside, that to me makes it look like their case isn't very good to begin with.
What more do they need? Compelling testimony from an uncooperative witness isn't necessary for a case, nor is it even very helpful: such a witness can't be considered reliable or trustworthy.
In your world guilty parties walk because the state has no power to make anyone do anything. Everything is based upon the prosecutor being Sherlock Holmes and always finding exactly what they need. The real world doesn't work that way.
Are the italicized qualifiers intended to mean something other than that?
If you're on trial for murder, the prosecution would never call on you to testify. Why would they? Of course you're going to claim that you didn't do it. Your testimony would be useless.
Murderers are tried with physical evidence linking them to the crime, and witness testimony from other people. Murderers don't even need to be present to be convicted; this happens sometimes if they're considered a danger in the courtroom, or have fled.
From a quick search, it appears that a trial in the US cannot begin without the defendant present, although it may proceed if they leave afterwards depending on circumstances.
It's self-evident that most of the actions of the criminal justice system are cruel. I think anyone would agree. However, that phrase in our constitution explicitly leaves the door open for our criminal justice system to perform cruel behaviors, as long as they are in line with the standards of the day (or, if you're an originalist, of the standards of 1791).
So, my response would be that you've tabled the only portion of the debate that is relevant. I'll freely concede that the criminal justice system is cruel, but I wouldn't then argue that the system falls afoul of the 8th amendment.
States convention, anyone?
I think there's a ton of opportunity to totally re-work the criminal justice system within the confines of the current amendments. I think that kind of change would be a lot more politically feasible in the near-term (as in, you could make such changes with 45-55% of the population's acceptance, rather than 65-80%).
The 8th amendment says "you can't be worse than X", but it doesn't put any constraints on how "good" we can make the system. I think the political reality is that we need to improve the system significantly before we can constitutionally constraint ourselves to that new bar.
Imprisoning people who have committed crimes is not cruel. It's literally the job of every justice system to do that.
If there was some sort of abuse then sure, but there hasn't been to my knowledge.
This makes it usual or common, but it doesn't make it not cruel.
> Imprisoning people who have committed crimes is not cruel.
Imprisoning someone is absolutely cruel. It may be common and accepted (and it certainly is in our current criminal justice system). It may even be just and proper, but it is still cruel.
That's not what is being called into question. It's imprisoning someone for the express purpose of coercing testimony that smells here.
All imprisonment is an attempt to constrain undesired and incentivize desired behavior by imposing unacceptable costs for non-compliance (in fact, so is all law); it is inherently coercive.
Depriving them of the ability to work and be a productive citizen. Depriving them of their existing assets (fines), and as stated by Manning and others, that grand juries have tended in the past to victimize those they call as witnesses.
[0]: https://en.wikipedia.org/wiki/Cruel_and_unusual_punishment
Unfair? Unnecessary? Unfitting of the wrong? Those are all things I don't know enough to really say or discuss in an educated manner.
Why would I assume you meant the colloquial "cruel" and not the legal "cruel" here? Perhaps you should edit to clarify if your intent was the former as opposed to the latter.
Perhaps you should also edit to clarify your intent.
This is the same line of reasoning Alex Jones uses to justify his conspiracies. "The government had Project Northwoods, why isn't [conspiracy] likely?!"
I personally don't like death penalties (due to their misuse as a political tool and the general high error rate of judgement) but I believe proper lethal injection fits perfectly within the bounds of not being cruel nor unusual.
So, if someone said that lethal injection was more humane if administered in direct sunlight while the injectee was hanging upside down due to blood movement some-such... assuming they were telling the truth about the efficacy then it'd likely pass the 8th amendment.
/I'll table the unusual bit.