Under the Sixth Amendment to the United States Constitution, all defendants in criminal trials are entitled to legal counsel. The text of the amendment reads as follows:
"In all criminal prosecutions, the accused shall enjoy the right to a speedy and public trial, by an impartial jury of the state and district wherein the crime shall have been committed, which district shall have been previously ascertained by law, and to be informed of the nature and cause of the accusation; to be confronted with the witnesses against him; to have compulsory process for obtaining witnesses in his favor, and to have the assistance of counsel for his defense." [Emphasis added]
Adding to the recognition of this right under the Constitution was the 1966 U.S. Supreme Court decision in Miranda v. Arizona, in which the court, in addition to reaffirming the defendant's Fifth Amendment right against self-incrimination, also reaffirmed the Sixth Amendment right to counsel:
". . .the person in custody must, prior to interrogation, be clearly informed that he has the right to remain silent, and that anything he says will be used against him in court; he must be clearly informed that he has the right to consult with a lawyer and to have the lawyer with him during interrogation, and that, if he is indigent, a lawyer will be appointed to represent him."
So, it is established that all defendants have a right to be represented by an attorney. Next comes the issue of ethical responsibilities that accompany admission into state bars. The American Bar Association, which represents and self-polices the legal profession, has as an important part of its code of conduct what is known as Rule 1.6, which establishes the requirement for attorneys to protect what is called "lawyer-client privilege." In other words, what one confides to one's attorney is protected information that the attorney is prohibited from disclosing without the client's consent. This rule, however, is not absolute, and allows for violations under the following circumstances:
"(b) A lawyer may reveal information relating to the representation of a client to the extent the lawyer reasonably believes necessary:
(1) to prevent reasonably certain death or substantial bodily harm;
(2) to prevent the client from committing a crime or fraud that is reasonably certain to result in substantial injury to the financial interests or property of another and in furtherance of which the client has used or is using the lawyer's services;
(3) to prevent, mitigate or rectify substantial injury to the financial interests or property of another that is reasonably certain to result or has resulted from the client's commission of a crime or fraud in furtherance of which the client has used the lawyer's services;
(4) to secure legal advice about the lawyer's compliance with these Rules;
(5) to establish a claim or defense on behalf of the lawyer in a controversy between the lawyer and the client, to establish a defense to a criminal charge or civil claim against the lawyer based upon conduct in which the client was involved, or to respond to allegations in any proceeding concerning the lawyer's representation of the client;
(6) to comply with other law or a court order; or
(7) to detect and resolve conflicts of interest arising from the lawyer’s change of employment or from changes in the composition or ownership of a firm, but only if the revealed information would not compromise the attorney-client privilege or otherwise prejudice the client.
(c) A lawyer shall make reasonable efforts to prevent the inadvertent or unauthorized disclosure of, or unauthorized access to, information relating to the representation of a client."
Now, we've established that everyone, no matter how heinous the crime, enjoys the right to legal counsel, and we've established that the otherwise sacrosanct principle of attorney-client privilege allows for exceptions under specified circumstances. Some of this is provided as background that may or not exceed the parameters of the question. What is certain, however, is that the suspect in a criminal act, no matter how vile the act, will have a lawyer, even if, which is very frequent given the socioeconomic background of most criminals, that lawyer is paid for by the taxpayers (i.e., public defenders). Other than public defenders, who are assigned cases, lawyers can choose not to represent an individual. Once the decision is made to represent that individual, however, the lawyer has a responsibility to defend the client/suspect irrespective of whether the lawyer believes the client/suspect to be guilty. Every single day, lawyers defend clients who they believe are guilty; the lawyer's job is to prevent the prosecutor from establishing guilt beyond a reasonable doubt. A lawyer who quits a case out of moral conviction will not be well respected among his or her peers, as the principle that everyone is entitled to legal representation is enshrined in law.