NRS 49.015 provides, generally:

49.015. Privileges recognized only as provided

1. Except as otherwise required by the Constitution of the
United States or of the State of Nevada, and except as provided in
this Title or Title 14 of NRS, no person has a privilege to:

(a) Refuse to be a witness;

(b) Refuse to disclose any matter;

(c) Refuse to produce any object or writing; or

(d) Prevent another from being a witness or disclosing any
matter or producing any object or writing.

2. This section does not:

(a) Impair any privilege created by Title 14 of NRS or by
the Nevada Rules of Civil Procedure which is limited to a particular
stage of the proceeding; or

(b) Extend any such privilege to any other stage of a
proceeding.

In general, then, a privilege exists when provided for by law. Next blog we'll begin to look at the most common privileges.