PEN §601: (a) Any person is guilty of trespass who makes a credible threat to cause serious bodily injury, as defined in subdivision (a) of Section 417.

(a) Any person is guilty of trespass who makes a credible threat to cause serious bodily injury, as defined in subdivision (a) of Section 417.6, to another person with the intent to place that other person in reasonable fear for his or her safety, or the safety of his or her immediate family, as defined in subdivision (l) of Section 646.9, and who does any of the following: (1) Within 30 days of the threat, unlawfully enters into the residence or real property contiguous to the residence of the person threatened without lawful purpose, and with the intent to execute the threat against the target of the threat. (2) Within 30 days of the threat, knowing that the place is the threatened person’s workplace, unlawfully enters into the workplace of the person threatened and carries out an act or acts to locate the threatened person within the workplace premises without lawful purpose, and with the intent to execute the threat against the target of the threat. (b) Subdivision (a) shall not apply if the residence, real property, or workplace described in paragraph (1) or (2) that is entered is the residence, real property, or workplace of the person making the threat. (c) This section shall not apply to any person who is engaged in labor union activities which are permitted to be carried out on the property by the California Agricultural Labor Relations Act, Part 3.5 (commencing with Section 1140) of Division 2 of the Labor Code, or by the National Labor Relations Act. (d) A violation of this section shall be punishable by imprisonment pursuant to subdivision (h) of Section 1170, or by imprisonment in a county jail not exceeding one year, or by a fine not exceeding two thousand dollars ($2,000), or by both that fine and imprisonment.