the first trial against a monarch in the uk was in 1649, ending in an execution. from wiki:
“On Saturday 27 January 1649, the parliamentarian High Court of Justice had declared Charles guilty of attempting to “uphold in himself an unlimited and tyrannical power to rule according to his will, and to overthrow the rights and liberties of the people” and he was sentenced to death by beheading”
the first trial against a monarch in the uk was in 1649, ending in an execution. from wiki:
“On Saturday 27 January 1649, the parliamentarian High Court of Justice had declared Charles guilty of attempting to “uphold in himself an unlimited and tyrannical power to rule according to his will, and to overthrow the rights and liberties of the people” and he was sentenced to death by beheading”
I can think of more than a few modern day monarchs and politicians that would be beheaded by those criteria…
Depending on your perspective, the law that was passed especially for the purpose of executing him was not legal.
They effectively committed regicide.
That’s why many people involved in that trial were executed, for regicide.