Final answer:
A lawyer must continue representation until a case concludes unless the client consents to withdrawal. This maintains the ethical standards legal professionals follow. The provision of public defenders ensures this right when a person cannot afford an attorney.
Step-by-step explanation:
Once a lawyer undertakes representation of a client, pro bono or paid, the lawyer must represent the client until the conclusion of the matter unless the client gives informed consent to withdraw. The options provided, such as the client disagreeing with the attorney's advice or the attorney being offered a more lucrative case, are not valid reasons for an attorney to terminate their representation according to ethical standards. It is also not generally acceptable for an attorney to withdraw based on an inability to secure legal fees once they have begun representation, especially in a pro bono case where no fees are anticipated.
This principle stems from the concept of the right to an attorney, which is fundamentally protected by the Sixth Amendment and reinforced by landmark cases like Gideon v. Wainwright. Defendants in criminal cases have the right to legal counsel, regardless of their ability to pay, thereby ensuring a fair trial and due process. Public defenders are provided for those who cannot afford private representation, signifying the importance of legal counsel in the judicial system.