Perjury is obstruction of justice, dude.
Perjury and obstruction are separate crimes and were listed and voted on separately in the Articles of Impeachment against Clinton.
You referred to him as if he was. Nixon was not impeached.
Again, I did not say he was impeach and I did not refer to him as if he was.
I said "the articles of impeachment against him included obstruction charges for "withholding relevant and material evidence or information from lawfully authorized investigative officers and employees of the United States...."
There were articles of impeachment drawn up against Nixon. That is a simple fact and does not imply he was actually impeached.
WRONG. It is defined by the Constitution and only the Constitution. 'High crimes' are those laws that BOTH Houses have passed and the President has signed as a 'high crime' and ONLY those laws.
Wrong. High crimes and misdemeanors is not defined in the Constitution and were not intended to be limited to strictly criminal acts. The articles against Clinton included "abuse of power." What constitutes treason is defined by federal law.
Who decides if something is not an impeachable offense if Congress votes to impeach?
You have told us the Supreme Court has no authority to interpret the Constitution, so the courts obviously cannot determine what "high crimes and misdemeanors" actually means.
In reality, the SC would likely say it is a "political question" which they would not intervene.
Alan Dershowitz in "The Case Against Impeaching Donald Trump" says historically a misdemeanor involved governmental actions (his book was originally entitled "The Case Against Impeaching Hillary Clinton").