Tom a murderer?

With regard to the case of Tom the murderer. It has been said that a lawyer should not be forced to defend him in the following case: Tom admits to committing the murder. It has been said that a lawyer should not have to defend someone that he knows is guilty because it would be introducing a harm. However, even if the lawyer can be certain of Tom's guilt (which I posit he may not be on Tom's testimony alone) he is NOT introducing a harm by defending Tom. The adversarial judicial system has been developed as a crucible for melting away the slag to get to the facts of the case. If there is no pressure from the defense the crucible will crack from the overwhelming pressure of the state. Tom is owed legal defense to ensure that he is receiving that which he JUSTLY deserves. If the means by which we convict Tom are faulty then the sentence that is produced for Tom is also faulty. Furthermore, the requirement of a legal defense is also for the purpose of protecting oneself from oneself. It is inherently possible that Tom might admit to the murder out of coercion. It might be the case that he is being paid to take the hit for some Mobster. In which case the legal defense will protect him from that as well. Perhaps Tom is mentally unstable, and claims to have committed the murder out of some misguided desire for notoriety. The point is that ones own admission and confession does not prove guilt and the mechanisms of the judicial system are for the purpose of proving guilt or innocence in the most objective way possible. For this reason, the last lawyer in town has NO moral right to opt out.
Even if Tom is ACTUALLY guilty the lawyer certainly does not defame his own character by defending Tom. In fact by defending Tom he is demonstrating his good character by seeking the higher goods of Truth and Justice. The lawyer's service in the judicial system is for that purpose. The real harm then would be not defending Tom.
The case of the Physician in Physician Assisted Suicide is not analogous to the above case of the lawyer defending the guilty. The conditions are completely different. While the function of the lawyer is to make the wheels of justice turn, to engage in a logical and adversarial fact finding mission in order to promote the Goods of Truth and Justice, the Physician's function is to promote Health and the inherent beauty of Healthy Life. Even if the Physician's function includes PAS it would only make the difference that much greater because the Physician does not attempt to discern the objective truth of a possible crime that is what really happened; No his function, his craft is the care of the body and not the craft of Rhetoric and Logic. Both have some responsibility for the things that happen to those in their charge, but their difference in function makes all the difference in the world. Justice is concerned with what someone deserves according to what acts he as committed and intended et cetera. 'Physic' on the other hand is merely concerned with the continued existence of the physical body.
While the charge of a lawyer may be sentenced to death, the lawyer's part in this was to help ensure that this was really deserved or not based on the truth of the matter insofar as the court has been able to discern. He is not held accountable for that because he did his part in promoting the good of Justice. The Physician on the other hand is himself directly an arbiter of Life and Death and so the things that come from his hand do weigh upon his conscience. It seems appropriate that a Physician should be able to opt out of PAS and have a right to do so even as everyone has the right to legal counsel. It would be he who made the decision to comply with the patient's request and he who prescribed the lethal dose, he who knowingly assented to this.
So if the Physician has moral objections to being a part of PAS then his right to refuse consent should be upheld. Notice that the lawyer on the other hand prescribes nothing, and wills nothing except the rule of law and justice for all.