Authored by Alan Dershowitz via The Gatestone Institute,

The effort to find (or create) impeachable offense against President Donald Trump has now moved from the subjects of the Mueller investigation -- collusion with Russia and obstruction of justice -- to alleged recent political "sins": "quid pro quo" with Ukraine and obstruction of Congress.

The goal of the impeach-at-any-cost cadre has always been the same: impeach and remove Trump, regardless of whether or not he did anything warranting removal. The means -- the alleged impeachable offenses -- have changed, as earlier ones have proved meritless. The search for the perfect impeachable offense against Trump is reminiscent of overzealous prosecutors who target the defendant first and then search for the crime with which to charge him. Or to paraphrase the former head of the Soviet secret police to Stalin: show me the man and I will find you the crime.

Although this is not Stalin's Soviet Union, all civil libertarians should be concerned about an Alice in Wonderland process in which the search for an impeachable crime precedes the evidence that such a crime has actually been committed.

Before we get to the current search, a word about what constitutes an impeachable crime under the constitution, whose criteria are limited to treason, bribery or other high crimes and misdemeanors. There is a debate among students of the constitution over the intended meaning of "high crimes and misdemeanors." Some believe that these words encompass non-criminal behavior. Others, I among them, interpret these words more literally, requiring at the least criminal-like behavior, if not the actual violation of a criminal statute.

What is not debatable is that "maladministration" is an impermissible ground for impeachment. Why is that not debatable? Because it was already debated and explicitly rejected by the framers at the constitutional convention. James Madison, the father of our Constitution, opposed such open-ended criteria, lest they make the tenure of the president subject to the political will of Congress. Such criteria would turn our republic into a parliamentary democracy in which the leader -- the prime minister -- is subject to removal by a simple vote of no confidence by a majority of legislators. Instead, the framers demanded the more specific criminal-like criteria ultimately adopted by the convention and the states.

Congress does not have the constitutional authority to change these criteria without amending the Constitution. To paraphrase what many Democratic legislators are now saying: members of Congress are not above the law; they take an oath to apply the Constitution, not to ignore its specific criteria. Congresswoman Maxine Waters placed herself above the law when she said:

"Impeachment is about whatever the Congress says it is. There is no law that dictates impeachment. What the Constitution says is 'high crimes and misdemeanors,' and we define that."

So, the question remains: did President Trump commit impeachable offenses when he spoke on the phone to the president of Ukraine and/or when he directed members of the Executive Branch to refuse to cooperate, absent a court order, with congressional Democrats who are seeking his impeachment?

The answers are plainly no and no. There is a constitutionally significant difference between a political "sin," on the one hand, and a crime or impeachable offenses, on the other.

Even taking the worst-case scenario regarding Ukraine -- a quid pro quo exchange of foreign aid for a political favor -- that might be a political sin, but not a crime or impeachable offense.

Many presidents have used their foreign policy power for political or personal advantage.

Most recently, President Barack Obama misused his power in order to take personal revenge against Israeli Prime Minister Benjamin Netanyahu. In the last days of his second term, Obama engineered a one-sided UN Security Council resolution declaring that Israel's control over the Western Wall -- Judaism's holiest site -- constitutes a "flagrant violation of international law." Nearly every member of Congress and many in his own administration opposed this unilateral change in our policy, but Obama was determined to take revenge against Netanyahu, whom he despised. Obama committed a political sin by placing his personal pique over our national interest, but he did not commit an impeachable offense.

Nor did President George H. W. Bush commit an impeachable offense when he pardoned Caspar Weinberger and others on the eve of their trials in order to prevent them from pointing the finger at him.

This brings us to President Trump's directive with regard to the impeachment investigation. Under our constitutional system of separation of powers, Congress may not compel the Executive Branch to cooperate with an impeachment investigation absent court orders. Conflicts between the Legislative and Executive Branches are resolved by the Judicial Branch, not by the unilateral dictate of a handful of partisan legislators. It is neither a crime nor an impeachable offense for the president to demand that Congress seek court orders to enforce their demands. Claims of executive and other privileges should be resolved by the Judicial Branch, not by calls for impeachment.