How is “compelling inaction” anything but a synonym for “prison”?

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?

I'm not sure how compelling someone to testify is at all productive. If someone isn't willing to voluntarily testify, then what makes you think their testimony will be reliable and true? If I were sitting on a jury, I would take the testimony of someone unwilling to testify with a large grain of salt.

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.

Note that lying under oath is also a crime, so also not a good plan.

Maybe not, but people absolutely do it all the time. Convictions for perjury are rare, probably because it's way too much work to prove to a jury beyond a reasonable doubt that the witness absolutely knew they were lying when they made a statement that isn't corroborated by other evidence or witnesses.

If you won't follow our rules, I'll make another rule that says you have to!

How do you envision that playing out? If the court has no power to compel testimony they have very little power in general.

How do you figure? They have the power to allow prosecutors to present physical evidence, and to allow testimony from cooperative witnesses. Then they have the power to have a trial based on this evidence, and then find a suspect guilty or not guilty. If they find the suspect guilty, they have the power to impose a sentence.

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.

And what if you can't obtain that evidence because the person in possession won't hand it over? What if your only 'witness' is a corporate entity? What if your witness just doesn't like cops? Probably a hundred more scenarios I can't come up with at the moment.

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.

I have a really hard time believing that the vast majority of convictions depend on uncooperative witness testimony.

Who ever said "vast majority"?

"Everything is based upon the prosecutor being Sherlock Holmes and always finding exactly what they need."

Are the italicized qualifiers intended to mean something other than that?

I’m on trial for murder. I don’t like my chances, so I’ll just stay home instead. They can’t make me show up, so I’m home free!

What does this have to do with anything?

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.

The comment I replied to disputed the general notion that courts need to be able to compel behavior.

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.

I don't think that's true: they have something called "trial in absentia". It doesn't happen often though.

I’m aware. The fact that there’s a name for it doesn’t mean it’s allowed in the US. https://en.wikipedia.org/wiki/Trial_in_absentia

Can a court coerce a murder witness to testimony with imprisonment?

In the US, no. The 5th Amendment protects defendants from being coerced into self-incrimination. I was just pointing out how his comment really made no sense here at all, since this article isn't about a criminal being coerced into testifying against themselves (which again is illegal per the 5A), but rather a witness being coerced into testifying when they don't want to for some reason.

You also dispute vaccines based on your comment history which would indicate an unwillingness to engage in rational conversation or to accept scientific facts.