When an attorney gives a proper level of attention and care to a particular case and fulfills all necessary obligations to a client, he is described as practicing reasonable diligence — also known as due diligence. This seemingly subjective term is reflective of the expectations in an attorney-client relationship, and it binds attorneys to certain protocols. Historically, there has been dispute over what the standards are for assessing reasonable diligence and where the burden of proof lies when the concept comes up in a court room.
An attorney is expected to fulfill contractual obligations to his client, regardless of his personal beliefs regarding the matter or case and regardless of personal minor inconveniences it may cause him. In other words, he cannot abandon or disregard the case or the legal matters involved in it. If a client accuses an attorney of not practicing reasonable diligence and the court upholds such an accusation, the most likely consequence will be disbarment. It is therefore vitally important that he maintains control over his workload, whether in regard to one client or several clients, as to prevent such an accusation from taking place.
Reasonable diligence is not absolute, as the word reasonable suggests. An attorney is not bound to take every whim of his client into account, particularly if such a client requests that he resort to unreasonable and unethical methods. He must practice discretion in order to avoid offensive, unprofessional, or not respectable tactics inside and outside of the court room. While the attorney is expected to serve his client thoroughly and zealously, he is additionally not always bound to reserve his work to only one client, as long as a controlled workload may be maintained.
The concept of reasonable diligence is most often reserved for attorney-client relationships, but this is not always the case. It may also be applied to matters involving an entire government. In countries whose citizens are guaranteed the right to a speedy trial, such as in the sixth amendment of the Constitution of the United States, a government is obligated to act with haste and refrain from procrastination.
Because of the subjective tendency of the concept, it is difficult to assess the standards for reasonable diligence. An attempt to prove that an attorney, or an entire government for that matter, did not apply enough effort in resolving a particular matter is not a clear-cut task. The burden of proof, however, does not always lie on the client. On occasion, the parties accused of failing to practice reasonable diligence must make their case rather than have the client attempt to prove that the attorney failed to fulfill his obligations.