Voting on academic files is governed by bylaw 55. At a minimum, each department must follow the guidelines in bylaw 55.
http://senate.universityofcalifornia.edu/bylaws-regulations/bylaws/blpart1.html#bl55
However, bylaw 55 is sufficiently broad and allows departments to further define within their own bylaws who will vote on which actions. Once defined, departments must provide a copy of the departmental voting bylaws to the Dean's Office Academic Personnel Staff.
Voting on academic appointments is further explained in PPM 230-20, http://adminrecords.ucsd.edu/ppm/docs/230-20.HTML, pg. 13, item F;
Voting on academic reviews is further explained in PPM 230-28, http://adminrecords.ucsd.edu/ppm/docs/230-28.HTML, on page 42, Item VIII.A.
Be careful to review policy as it relates to specific actions.
Starting on page 26 of PPM 230-28, you'll find descriptions of proposed actions. Within those descriptions are directions indicating which actions require a vote. Some actions may not require a vote per campus or UCOP policy, but may be an action requiring a vote in your departmental bylaws.
Since departments develop their own bylaws on voting, the Dean's Office does not provide advice on voting policy within each department.
Determining whether quorum has been met
In order for an action to be moved forward by the department, it must be supported by at least 50% of the departmental faculty "eligible to vote and in residence on campus in the quarter when the vote is taken" (PPM 230-20.V.F.).
Faculty who are on approved leaves and are away from campus are not counted for the purpose of determining the 50% minimum. Similarly, faculty members who have abstained due to a conflict or for administrative reasons (e.g., because they will serve as reviewers later in the process) are not counted for this purpose.
Those who are in residence but choose not to participate in the review or cast a vote are counted in the total number of eligible faculty for the purpose of determining the 50% minimum. For this reason, it is important that departments indicate on the Summary form how many absences are due to approved leaves and how many abstentions are for administrative reasons.
Ensuring department vote is valid
Departments should be sure to verify the validity of any department vote before sending files forward for review. A proposed action can only go forward if it is supported by a majority (50% or more) of faculty who are eligible to vote and are in residence at the time of the vote.
An approved leave is a valid reason for absence from campus. Faculty on approved leaves are not considered to be in residence, so they can be subtracted from the total number of faculty eligible to vote (as reported on the file Summary).
A faculty member who is in residence and eligible to vote, but who chooses not to attend the faculty meeting or vote, cannot be reported as absent from campus and cannot be subtracted from the total number of faculty eligible to vote.
Example: If a department has 45 faculty members who are eligible to vote on a proposed action, and three are away from campus on approved leaves, the number of faculty eligible to vote and in residence is 42. At least 50% (21) of these must support the proposed action in order for it to go forward.