Not one of them has tried.
When does a president become immune from prosecution of a crime?
Back when Richard Nixon was president, there was a debate about whether a sitting President could be prosecuted for a crime, or whether he had to be impeached first. That was never resolved, because Nixon resigned and Ford then pardoned him. Clinton similarly plea-bargained his case (though, interestingly, Starr didn't try to prosecute him before impeachment). So if some state AG tries to indict Obama, we will be in uncharted waters.
very interesting.
So....If a president committed murder he would have to be impeached first before he could be arrested, charged, and tried? ( Wow!)
I may need to read US v Nixon again. I thought the president could be charged prior to impeachment.