Why would he be entitled to “due process of the law” for an impeachment trial? An impeachment trial does not take place in a court of law, it takes place in the Illinois Senate.
He is entitled to the rules of the impeachment trial as set out in the Constitution. Nothing more.
I agree with what you said completely, but feel the explanation should be expanded a bit more, as there seems to be some confusion among the commentators.
An impeachment and trial are constitutional matters. As all courts and laws derive their authority (in this country, at least) from the constitution, such a proceeding cannot be subject to either civil or criminal laws and principles.
The term that best describes what is happening is that an impeachment is an “extralegal” process; that is, it exists outside of the laws, and as such the courts have no say in the matter, other to be ensure that the process is being followed as prescribed by the constitution.
Therefore, there can be no “due process of law”, as that term itself originates in the constitution. There can however be “due process of the constitution” which simply means that the constitutionally mandated procedure has to be followed.
This is the same reason that the “lawsuits” concerning Prop 8 in California are laughable, as they are asking the courts to apply laws to a constitutional amendment, which according to previous litigation, was properly conducted and must therefore be valid.
The libwack lawyers, as usual, get it backwards, stating that the Prop. 8 amendment is a violation of civil rights laws, when in fact any disagreement between the two can only be construed as meaning that the civil rights laws are now unconstitutional. Put another way, they want the legal tail to wag the constitutional dog.
Typical.