"'California courts have long recognized a common law right to fair procedure protecting individuals from arbitrary exclusion or expulsion from private organizations which control important economic interests . . . .' Fair procedure comes into play where private organizations are '"tinged with public stature or purpose"' or attain a '"quasi-public significance,"' as contrasted with purely private associations which have no larger '"purpose or stature than pleasant, friendly and congenial social relationships." (Delta Dental Plan v. Banasky (1994) 27 Cal. App. 4th 1598, 1607.) In determining whether a private association or organization is required to provide fair procedure before excluding or expelling members, the judicial inquiry is "focused on the practical power of the entity in question to affect substantially an important economic interest." ( Ezekial v. Winkley (1977) 20 Cal. 3d 267, 277, 142 Cal. Rptr. 418, 572 P.2d 32.) The preliminary question to be asked in determining whether adherence to fair procedure is required is whether the revocation of the privileges at issue would effectively impair an individual's right "'to fully practice his profession.'" (Ascherman v. Saint Francis Memorial Hosp. (1975) 45 Cal. App. 3d 507, 511, 119 Cal. Rptr. 507.) In addition, as a general rule, "membership in an association, with its associated privileges, once attained, is a valuable interest which cannot be arbitrarily withdrawn. This comports with the broader principle that one on whom an important benefit or privilege has already been conferred may enjoy legal protections not available to an initial applicant for the same benefit." (Ezekial v. Winkley, supra, 20 Cal. 3d at p. 273.) Accordingly, procedural fairness in the form of adequate notice of the charges brought against the individual and an opportunity to respond to those charges ( Smith v. Vallejo General Hospital (1985) 170 Cal. App. 3d 450, 457, 216 Cal. Rptr. 189) is an indispensable prerequisite for one's expulsion from membership in such a society or association, notwithstanding provisions to the contrary in the association's bylaws (Pinsker v. Pacific Coast Society of Orthodontists (1974) 12 Cal. 3d 541, 552-553, 116 Cal. Rptr. 245, 526 P.2d 253; see also Anton v. San Antonio Community Hosp. (1977) 19 Cal. 3d 802, 824, 140 Cal. Rptr. 442, 567 P.2d 1162). The foregoing principles have been applied to professional organizations, in which membership may be an economic necessity for pursuit of the profession, or which wield such power as to affect "significant economic and professional concerns[, clothing them] with a 'public interest.'" (Pinsker v. Pacific Coast Society of Orthodontists, supra, 12 Cal. 3d at pp. 550, 552, fn. omitted.) These principles also apply generally to all decisions concerning membership on a hospital staff. (Smith v. Vallejo General Hospital, supra, 170 Cal. App. 3d at p. 457; see also Miller v. Eisenhower Medical Center (1980) 27 Cal. 3d 614, 626-627, 166 Cal. Rptr. 826, 614 P.2d 258.) In addition, they have been applied to expulsion from a residency program (Ezekial v. Winkley, supra, 20 Cal. 3d at p. 270) and appear to apply to the revocation of provisional staff privileges (see, e.g., Bonner v. Sisters of Providence Corp. (1987) 194 Cal. App. 3d 437, 439-440, 239 Cal. Rptr. 530).