Rudy Giuliani, former mayor of New York. Photo: Al Drago/Bloomberg

I have been a defense lawyer in our nation's state and federal courts for more than forty years. I am very proud of that and most of my colleagues who call themselves defense lawyers feel the same way.  As a group we tend to be very independent, representing underdogs, minorities, outcasts and those rightly or wrongly accused.

We have our moments of financial success but since we often represent individuals and not by Fortune 500 companies, we typically struggle to make ends meet. We strive for a way of thinking that is akin to the lifestyle of our greatest predecessor, Clarence Darrow.

We defend against all odds or as one of us was heard to say: "Our defense is to be against all laws and all humanity." This was said by a famous French attorney who was saddled with the impossible task of representing a Nazi war criminal.  It is an extreme statement but it does explain the often desperate plight of defense lawyers.

It is a noble and honorable calling for those who live up to their oaths; to wit: "To preserve, protect and defend, the Constitution of the United States of America." So our mission is also patriotic. We have been described as the champions of liberty and freedom for all.

Defending against criminal charges or avoiding prosecution is what we do.  We hire investigators to research the complainants and to find the weak spots in the prosecution's case.  While some of us are involved in politics that is not our primary niche.  We are not generally engaged to dig up dirt on political opponents.  Mr. Giuliani's efforts in Ukraine are not part of any defense lawyer's job description.

Why is Mr. Giuliani engaged at all? Is it to tout the title of counsel to the president of the United States? Mr. Trump has not been charged with anything and while an impeachment inquiry has been started, Mr. Giuliani has made himself into a witness against his own client due to his own actions in Ukraine on behalf of Mr. Trump.  Mr. Giuliani's actions support the claims that Mr. Trump supported the involvement of Russians in our 2016 elections and is once again encouraging foreign interference in 2020.

As a witness to substantial and material facts in the impeachment inquiry, Mr. Giuliani must be disqualified from representing Mr. Trump. While the president cannot be prosecuted while in office, Mr. Giuliani certainly can be.

Thomas Liotti is a past president of the New York State Association of Criminal Defense Lawyers and former chair of the New York State Bar Association's Criminal Justice Section.