The Difference Between Formal Discovery and Investigation
Section 2031 provides that a "party may demand that any other party allow the party making the demand, or someone acting on that party's behalf, to enter on any land or other property that is in the possession, custody, or control of the party on whom the demand is made, and to inspect and to measure, survey, photograph, test, or sample the land or other property, or any designated object or operation on it." ( 2031, subd. (a)(3), italics added.)
In section 2031 as throughout the Discovery Act, "may" is quite obviously permissive.
It means that a party who wants to can conduct discovery.
If he doesn't want to, he doesn't have to. (Lowry v. Henry Mayo Newhall Memorial Hospital (1986) 185 Cal. App. 3d 188, 193 229 Cal. Rptr. 620, 64 A.L.R.4th 1191.)
There is scant authority on the distinction between formal discovery and investigation, with everyone apparently assuming that everyone else knows the difference. (E.g., 500 Motors, Inc. v. Superior Court (1981) 122 Cal. App. 3d 827, 829, fn. 1 176 Cal. Rptr. 349 describing a situation where "investigation (not formal discovery) is all that is needed" to find a document relevant to the issue before the court.)
Black's Law Dictionary defines "investigate" THIS WAY:
"To inquire into (a matter) systematically . . . ." "Discovery" is defined as "compulsory disclosure, at a party's request, of information that relates to the litigation . . . ." (Black's Law Dict. (7th ed. 1999) at pp. 478, 830.)