Ironically, one of the most useful things Trump could do is prosecute e.g. Hunter Bide so SCOTUS can strike down preëmptive pardons.
FWIW I think you're not correct here, or rather, it's not merely irrelevant but would actually harm them. The pardon power protects against criminal prosecution by the federal government. But it doesn't protect against mere embarrassment, nor against new actions performed after the pardon. Congress isn't prosecution, their inquiries are just about information finding, and while they can result in information on crimes surfacing, whether or not the USDOJ decides to pursue that or not is completely up to them. The reason a pardon might flat out hurt in such a scenario is that there is an argument it would eliminate any claim of 5th Amendment privileges. That's commonly referred to the right to be silent, and normally that's effectively what it is, but the actual right is the right against self incrimination [0]. If you've been pardoned for something purely federal then by definition it's impossible to incriminate yourself regarding that, because no criminal case can be brought against you. So there'd be no right to refuse to cooperate with a congressional inquiry, and if you didn't that could be treated as contempt which would not be covered by any pardon for the underlying actions.
So yes if a future Administration wanted to pursue criminal prosecutions for crimes that were undertaken by the current Trump Administration, Trump's pardons could certainly put a stop to that. But in terms of "they can basically turn these folks' lives into a living hell of back-to-back hearings", pardons don't help with that one. And if the Democrats just wanted to thoroughly document exactly what went down and who was responsible to make it an indelible part of the history books, with any social consequences that'd come from that, pardons can't help with that either.
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0: Text of the 5th Amendement: "...nor shall be compelled in any criminal case to be a witness against himself..."
Trump has so thoroughly poisoned the well on the "weaponized DOJ / weaponized IRS / weaponized Congressional investigations" that the Democrats, having no spine, won't bother doing any of that.
They also didn't prosecute GWB/Cheney/Rumsfeld for war crimes when they had the chance. This is a long standing policy of theirs.
Not relevant to domestic crimes committed by non-Cabinet folk.
If they won't even investigate the wholesale murder of civilians by the command of the White House and CIA and prosecute those reaponsbile for murder and torture then what hope is there that they'll hold Trump and co to account?
A consistent mistake by the Democrats is thinking foreign policy will win votes. It doesn’t. We’re the centre of the empire and that makes us arrogant and self centred. You can’t win a national election based on war crimes.
Trump won votes in 2024 based on how he said he would handle several foreign policy issues: NATO, Ukraine, Palestine, tariffs, China, and Iran, so I'm not sure what you're getting at here.
> You can’t win a national election based on war crimes.
This clearly is the case, so do the prosecutions after winning the election and running on domestic issues. To do anything less is to both give up the moral high ground and endorse the war crimes by not vigorously investigating them.
Why? If Democrats take the House in the midterms, which looks more likely the longer Navarro and Musk have West Wing access, they can basically turn these folks' lives into a living hell of back-to-back hearings (and contempt charges down the road). And if Democrats win the next election, they'll presumably put someone with a pulse in charge who doesn't take two years to bring the most important cases of their administration to the docket.