What is the importance of attorney-client relationship?

In Smith v. Superior Court (1968) 68 Cal.2d 547, 561, 68 Cal.Rptr. 1, 440 P.2d 65: we emphasized the importance of the attorney-client relationship: "it involves not just the casual assistance of a member of the bar, but an intimate process of consultation and planning which culminates in a state of trust and confidence between the client and his attorney. This is particularly essential, of course, when the attorney is defending the client's life or liberty." We also confirmed that the same intimate relationship must prevail whether the attorney is retained or appointed. "To hold otherwise would be to subject that relationship to an unwarranted and invidious discrimination arising merely from the poverty of the accused." (Id., p. 562, 68 Cal.Rptr. p. 10, 440 P.2d p. 74.)