Under which rule is the lawyer's duty of loyalty to clients established?

The duty of loyalty to clients is primarily established under Rule 1.7 of the Model Rules of Professional Conduct, which addresses conflicts of interest in the representation of clients. This rule emphasizes that a lawyer must avoid representing clients if there is a concurrent conflict of interest, which arises when the representation of one client will be directly adverse to another client or when there is a significant risk that the lawyer’s ability to consider, recommend, or carry out a course of action for one client will be adversely affected by the lawyer's responsibilities to another client or by the lawyer's own financial, business, property, or personal interests.

The purpose of Rule 1.7 is to ensure that lawyers maintain undivided loyalty to each client, which is a foundational aspect of the attorney-client relationship. This duty is critical because it protects clients from potential harm that can arise from divided loyalties and ensures that they receive the lawyer’s full attention and dedication to their legal matters.

In contrast, other rules mentioned address different aspects of professional conduct. For instance, Rule 6.1 pertains to a lawyer's responsibility to provide pro bono services, while Rule 1.8 deals with specific rules regarding conflicts of interest, particularly concerning certain transactions between a lawyer and a client.