Article one, clause 5: “ The House of Representatives shall choose their Speaker and other Officers; and shall have the sole Power of Impeachment. “
So the dims are interpreting this to mean they don’t need the courts for any impeachment proceedings, including the validity of their subpoenas.
And they believe this clause allows them to run to roughshod over the rest of the Constitution that does not grant them certain powers that they want to wield anyway?
It is actually Article I, Section II; which is what you are referring to, JP.
Further, the democrats do need the Judiciary Branch because the Chief Justice of the Supreme Court would preside over the impeachment of a President (Article I, Section III).