California Code, Government Code - GOV § 31720.5

(a) If a safety member, a firefighter member, or a member in active law enforcement who has completed five years or more of service under a pension system established pursuant to Chapter 4 (commencing with Section 31900) or under a pension system established pursuant to Chapter 5 (commencing with Section 32200) or both or under this retirement system or under the State Employees' Retirement System or under a retirement system established under this chapter in another county, and develops heart trouble, that heart trouble developing or manifesting itself in those cases shall be presumed to arise out of and in the course of employment. That heart trouble developing or manifesting itself in those cases shall in no case be attributed to any disease existing prior to such development or manifestation.

(b) The presumption described in subdivision (a) is rebuttable by other evidence. Unless so rebutted, the board is bound to find in accordance with the presumption.

(c) As used in this section, “firefighter member” includes a member engaged in active fire suppression who is not classified as a safety member.

(d) As used in this section, “member in active law enforcement” includes a member engaged in active law enforcement who is not classified as a safety member.

(e) The presumption described in subdivision (a) shall additionally apply to a firefighter member or member in active law enforcement following termination of service for a period of 3 calendar months for each full year of the requisite service, but shall not exceed 60 months regardless of the member's length of service, commencing with the last date that member actually worked as a firefighter member or member in active law enforcement.