In dealing with disruptive/oppositional parents, educators have recourse to the California Education Code and the California Penal Code. The following sections of the Penal Code apply to these parents, depending upon the circumstances: 

240. An assault is an unlawful attempt, coupled with a present ability, to commit a violent injury on the person of another.

241. (a) An assault is punishable by a fine not exceeding one thousand dollars ($1,000), or by imprisonment in the county jail not exceeding six months, or by both the fine and imprisonment.

241.2. (a) When an assault is committed on school or park property against any person, the assault is punishable by a fine not exceeding two thousand dollars ($2,000), or by imprisonment in the county jail not exceeding one year, or by both such fine and imprisonment. 
(b) "School," as used in this section, means any elementary school, junior high school, four-year high school, senior high school, adult school or any branch thereof, opportunity school, continuation high school, regional occupational center, evening high school, technical school, or community college. 

241.3. (a) When an assault is committed against any person on the property of, or on a motor vehicle of, a public transportation provider, the offense shall be punished by a fine not to exceed two thousand dollars ($2,000), or by imprisonment in a county jail not to exceed one year, or by both the fine and imprisonment. 
(b) As used in this section, "public transportation provider" means a publicly or privately owned entity that operates, for the transportation of persons for hire, a bus, taxicab, streetcar, cable car, trackless trolley, or other motor vehicle, including a vehicle operated on stationary rails or on a track or rail suspended in air, or that operates a school bus. 
(c) As used in this section, "on the property of" means the entire station where public transportation is available, including the parking lot reserved for the public who utilize the transportation system. 

241.4. An assault is punishable by fine not exceeding one thousand dollars ($1,000), or by imprisonment in the county jail not exceeding six months, or by both. When the assault is committed against the person of a peace officer engaged in the performance of his or her duties as a member of a police department of a school district pursuant to Section 39670 of the Education Code, and the person committing the offense knows or reasonably should know that the victim is a peace officer engaged in the performance of his or her duties, the offense shall be punished by imprisonment in the county jail not exceeding one year or by imprisonment in the state prison. 

241.6. When an assault is committed against a school employee engaged in the performance of his or her duties, or in retaliation for an act performed in the course of his or her duties, whether on or off campus, during the school day or at any other time, and the person committing the offense knows or reasonably should know the victim is a school employee, the assault is punishable by imprisonment in a county jail not exceeding one year, or by a fine not exceeding two thousand dollars ($2,000), or by both the fine and imprisonment. For purposes of this section, "school employee" has the same meaning as defined in subdivision (d) of Section 245.5. This section shall not apply to conduct arising during the course of an otherwise lawful labor dispute. 

242. A battery is any willful and unlawful use of force or violence upon the person of another. 

243. A battery is punishable by a fine not exceeding two thousand dollars ($2,000), or by imprisonment in a county jail not exceeding six months, or by both that fine and imprisonment.
(a) Except as otherwise provided in Section 243.6, when a battery is committed on school property, park property, or the grounds of a public or private hospital, against any person, the battery is punishable by a fine not exceeding two thousand dollars ($2,000), or by imprisonment in the county jail not exceeding one year, or by both the fine and imprisonment. 
(b) For the purposes of this section, the following terms have the following meanings: "School" means any elementary school, junior high school, four-year high school, senior high school, adult school or any branch thereof, opportunity school, continuation high school, regional occupational center, evening high school, technical school, or community college. 
(c) This section shall not apply to conduct arising during the course of an otherwise lawful labor dispute. 

243.3. When a battery is committed against the person of an operator, driver, or passenger on a bus, taxicab, streetcar, cable car, trackless trolley, or other motor vehicle, including a vehicle operated on stationary rails or on a track or rail suspended in the air, used for the transportation of persons for hire, or against a school bus driver, or against the person of a station agent or ticket agent for the entity providing the transportation, and the person who commits the offense knows or reasonably should know that the victim, in the case of an operator, driver, or agent, is engaged in the performance of his or her duties, or is a passenger the offense shall be punished by a fine not exceeding ten thousand dollars ($10,000), or by imprisonment in a county jail not exceeding one year, or by both that fine and imprisonment. If an injury is inflicted on that victim, the offense shall be punished by a fine not exceeding ten thousand dollars ($10,000), or by imprisonment in a county jail not exceeding one year or in the state prison for 16 months, or two or three years, or by both that fine and imprisonment. 

243.35. (a) Except as provided in Section 243.3, when a battery is committed against any person on the property of, or in a motor vehicle of, a public transportation provider, the offense shall be punished by a fine not to exceed two thousand dollars ($2,000), or by imprisonment in a county jail not to exceed one year, or by both the fine and imprisonment. 
(b) As used in this section, "public transportation provider" means a publicly or privately owned entity that operates, for the transportation of persons for hire, a bus, taxicab, streetcar, cable car, trackless trolley, or other motor vehicle, including a vehicle operated on stationary rails or on a track or rail suspended in air, or that operates a school bus. 
(c) As used in this section, "on the property of" means the entire station where public transportation is available, including the parking lot reserved for the public who utilize the transportation system. 

243.5. (a) When a person commits an assault or battery on school property during hours when school activities are being conducted, a peace officer may, without a warrant, notwithstanding paragraph (2) or (3) of subdivision (a) of Section 836, arrest the person who commits the assault or battery: 
(1) Whenever the person has committed the assault or battery, although not in the peace officer's presence.
(2) Whenever the peace officer has reasonable cause to believe that the person to be arrested has committed the assault or battery, whether or not it has in fact been committed. 
(b) "School," as used in this section, means any elementary school, junior high school, four-year high school, senior high school, adult school or any branch thereof, opportunity school, continuation high school, regional occupational center, evening high school, technical school, or community college. 

243.6. When a battery is committed against a school employee engaged in the performance of his or her duties, or in retaliation for an act performed in the course of his or her duties, whether on or off campus, during the school day or at any other time, and the person committing the offense knows or reasonably should know that the victim is a school employee, the battery is punishable by imprisonment in a county jail not exceeding one year, or by a fine not exceeding two thousand dollars ($2,000), or by both the fine and imprisonment. However, if an injury is inflicted on the victim, the battery shall be punishable by imprisonment in a county jail for not more than one year, or by a fine of not more than two thousand dollars ($2,000), or by imprisonment in the state prison for 16 months, or two or three years. 

For purposes of this section, "school employee" has the same meaning as defined in subdivision (d) of Section 245.5. 
This section shall not apply to conduct arising during the course of an otherwise lawful labor dispute. 

243.8. (a) When a battery is committed against a sports official immediately prior to, during, or immediately following an interscholastic, intercollegiate, or any other organized amateur or professional athletic contest in which the sports official is participating, and the person who commits the offense knows or reasonably should know that the victim is engaged in the performance of his or her duties, the offense shall be punishable by a fine not exceeding two thousand dollars ($2,000), or by imprisonment in the county jail not exceeding one year, or by both that fine and imprisonment. 
(b) For purposes of this section, "sports official" means any individual who serves as a referee, umpire, linesman, or who serves in a similar capacity but may be known by a different title or name and is duly registered by, or a member of, a local, state, regional, or national organization engaged in part in providing education and training to sports officials. 

245.5. (a) Every person who commits an assault with a deadly weapon or instrument, other than a firearm, or by any means likely to produce great bodily injury upon the person of a school employee, and who knows or reasonably should know that the victim is a school employee engaged in the performance of his or her duties, when that school employee is engaged in the performance of his or her duties, shall be punished by imprisonment in the state prison for three, four, or five years, or in a county jail not exceeding one year. 
(b) Every person who commits an assault with a firearm upon the person of a school employee, and who knows or reasonably should know that the victim is a school employee engaged in the performance of his or her duties, when the school employee is engaged in the performance of his or her duties, shall be punished by imprisonment in the state prison for four, six, or eight years, or in a county jail for not less than six months and not exceeding one year. 
(c) Every person who commits an assault upon the person of a school employee with a stun gun or taser, and who knows or reasonably should know that the person is a school employee engaged in the performance of his or her duties, when the school employee is engaged in the performance of his or her duties, shall be punished by imprisonment in a county jail for a term not exceeding one year or by imprisonment in the state prison for two, three, or four years. 

This subdivision shall not be construed to preclude or in any way limit the applicability of Section 245 in any criminal prosecution. 
(d) As used in the section, "school employee" means any person employed as a permanent or probationary certificated or classified employee of a school district on a part-time or full-time basis, including a substitute teacher. "School employee," as used in this section, also includes a student teacher, or a school board member. "School," as used in this section, has the same meaning as that term is defined in Section 626. 

602. Except as provided in Section 602.8, every person who willfully commits a trespass by any of the following acts is guilty of a misdemeanor: . . . 

(p) Refusing or failing to leave a public building of a public agency during those hours of the day or night when the building is regularly closed to the public upon being requested to do so by a regularly employed guard, watchman, or custodian of the public agency owning or maintaining the building or property, if the surrounding circumstances are such as to indicate to a reasonable person that the person has no apparent lawful business to pursue.

647b. Every person who loiters about any school in which adults are in attendance at courses established pursuant to Chapter 10 (commencing with Section 52500) of Part 28 of the Education Code, and who annoys or molests any person in attendance therein shall be punished by a fine of not exceeding one thousand dollars ($1,000) or by imprisonment in the county jail for not exceeding six months, or by both such fine and imprisonment. 

653g. Every person who loiters about any school or public place at or near which children attend or normally congregate and who remains at any school or public place at or near which children attend or normally congregate, or who reenters or comes upon a school or place within 72 hours, after being asked to leave by the chief administrative official of that school or, in the absence of the chief administrative official, the person acting as the chief administrative official, or by a member of the security patrol of the school district who has been given authorization, in writing, by the chief administrative official of that school to act as his or her agent in performing this duty, or a city police officer, or sheriff or deputy sheriff, or Department of the California Highway Patrol peace officer is a vagrant, and is punishable by a fine of not exceeding one thousand dollars ($1,000) or by imprisonment in the county jail for not exceeding six months, or by both the fine and the imprisonment. 

As used in this section, "loiter" means to delay, to linger, or to idle about a school or public place without lawful business for being present.