I answer not as a Catholic, but as an American and a Christian.
The State, not you, bears the burden of proof in this matter. Unless they are able to bear that burden in court, your client should walk. You are not suborning perjury, you are not doing anything which is outside the canons of ethics. Warm, fuzzy pronouncements about “the moral law”, the “higher law”, or God’s law, are not your concern, Counsel. You took an oath when you were sworn in as a member of the Bar to zealously represent your client within the perimeters of legal ethics, and that alone should be your concern.
Good American men and women have fought and died so that everyone–and I mean, EVERYONE-- in this country can have those procedural due process rights which your client will enjoy at trial. If your client is found not guilty, then such is the will of a sovereign God: perhaps His will is that “divine justice” will take place withn a different venue than the courtroom. As an advocate, you are not afforded the luxury of determining guilt. Even if your client “said he’s guilty”, that is not his concern, either: he is a lawman, unschooled in the laws of evidence. That evidence presented within the courtroom alone will determine his guilt.
**Pay no attention whatsoever to third parties who advise you to “tell him to plead guilty”: they have no more standing in all of this than a bartender would have in advising a surgeon on how to perform an appendectomy. *How ***your client pleads, and how you advise him to plead, are between him and you. Ultimately, it is HIS decision. And if you think that you can either win based upon insufficient evidence, or that the outcome after trial will result in either a better circumstance for your client than a negotiated or blind plea-- then you should put it on. After all, you’re the professional here, and it will be your reputation as an advocate that’s on the line.
**Never apologize for what you do in court, Counsel, for without you, the U. S. Constitution would be nothing more than mere parchment in the National Archives. Because of defense attorneys like yourself, those ideals which we hold dear as Americans become more than platitutes: they become reality, not only for the ones we cherisish in our society, but more importantly, for those we often (with some justification) despise. **