JUST WATCHEDFrustrated Manafort emailed Gates: WTF?ReplayMore Videos …MUST WATCH (15 Videos)Frustrated Manafort emailed Gates: WTF?Remind me … who is Paul Manafort?Day 9 of Manafort trial begins with mysteryJudge: ‘Probably wrong’ to scold prosecutorsAccountants: Manafort falsified loan documentsJury seated in Paul Manafort trial5 witnesses named in Paul Manafort trial Manafort’s journey to center of Mueller’s investigationAP may have led FBI to Manafort storage unitJudge revokes Manafort bail, sends him to jailMueller: Manafort attempted witness tamperingManafort campaign ties now part of Mueller investigationJudge rejects Manafort’s effort to dismiss caseJudge in Manafort case: Mueller aims to hurt TrumpManafort’s history in the political spotlightLaura Coates is a CNN legal analyst. She is a former assistant US attorney for the District of Columbia and trial attorney in the Civil Rights Division of the Department of Justice. She is the host of “The Laura Coates Show” on SiriusXM. Follow her @thelauracoates. The views expressed are her own. View more opinion articles at CNN. (CNN)In the history of criminal trials, no prosecutor has ever had the privilege of calling Mother Teresa as a witness. The existence of a perfect witness, void of credibility issues, or a proverbial skeleton in his or her closet is a pure fantasy. Yet, the defense counsel in Paul Manafort’s trial seems resolute in its efforts to discredit Rick Gates by painting him as an adulterous, immoral, unethical and corrupt liar in the hopes that the jury’s disdain for his character will fatally undermine his credibility as a testifying witness. Good luck. Do you know who testifies against pimps? Prostitutes. Do you know who testifies against drug dealers? Drug users. Do you know who testifies against conspirators? Their co-conspirators. In the imperfect contest of credibility, juries don’t hear from the criminally pristine, they hear from two evils and choose to believe the lesser. In this case, the jury will choose between the admitted liar and the accused one. Rick Gates' brutal lesson for Paul Manafort Ever since Rick Gates entered into a plea agreement and formally agreed to cooperate with the Robert Mueller-led criminal probe into possible collusion between members of the Trump presidential campaign and Russia, the public has anticipated his testimony. They imagined the dramatic courtroom scene that would unfold as Manafort’s right-hand man turned on him in the interests of self-preservation. Would there be consternation or reticence? Would the prosecution have to twist his arm and repeatedly remind him of his cooperation agreement? Would Gates break down on the stand and plead for Manafort’s forgiveness? Read MoreBut from the moment Gates took the stand, it was instantly evident that the public — and perhaps the media — had grossly overestimated Gates’s loyalty to Manafort. Not only did Gates admit to embezzling funds from Paul Manafort, he welcomed the chance to testify against him, and showed not one iota of regret for capitalizing on that opportunity. There is, apparently, no honor among (alleged) thieves. Who is Rick Gates?Is Gates a sympathetic witness? No. Is Gates a credible witness? Yes. His testimony, albeit mired by his self-interest and criminality, is not mired in contradiction. It is corroborated by the testimony of far more benign characters such as Manafort’s own accountants (some of whom have been immunized) and supporting documents whose authenticity has not been challenged. Documents have neither skeletons in their closet, undisclosed offshore accounts, tax obligations, immunity deals or London apartments used to conceal transatlantic extramarital affairs. It would be a mistake for defense lawyers to ignore the gravitas of documents that speak for themselves –and instead follow a singular strategy of attacking Gates’s seedy character. Ironically, Manafort’s heavy-handed attack on Gates’s credibility, may force his own hand to testify. Once the prosecution rests its case, Manafort will have the opportunity to present a case in his own defense, including the opportunity to take the stand and convince the jury that he was indeed the hapless and unaware mastermind betrayed by his student that his opening statement described. Follow CNN OpinionJoin us on Twitter and FacebookIf he chooses to testify, he will risk being questioned by prosecutors fixated on his jugular. But if he chooses not to testify, he will risk giving Gates the last word. Doing so would undermine his defense considerably. Although the jury would be specifically instructed not to infer the defendant is guilty if he chooses not to testify, the jury is comprised of human beings who are often incapable of disregarding damning evidence when the defendant has offered no rebuttal. Manafort’s defense team should not hang its hat on the likeability of Rick Gates. In a trial that has led to Manafort being berated over his penchant for ostrich-skinned clothing, he should remember the well-known adage resonating in the jury room: Birds of a feather flock together.