RCW 9A.16.020
Use of force—When lawful.
The use, attempt, or offer to use force upon or toward the person of another is not unlawful in the following cases:
(1) Whenever necessarily used by a public officer in the performance of a legal duty, or a person assisting the officer and acting under the officer's direction;
(2) Whenever necessarily used by a person arresting one who has committed a felony and delivering him or her to a public officer competent to receive him or her into custody;
(3) Whenever used by a party about to be injured, or by another lawfully aiding him or her, in preventing or attempting to prevent an offense against his or her person, or a malicious trespass, or other malicious interference with real or personal property lawfully in his or her possession, in case the force is not more than is necessary;
(4) Whenever reasonably used by a person to detain someone who enters or remains unlawfully in a building or on real property lawfully in the possession of such person, so long as such detention is reasonable in duration and manner to investigate the reason for the detained person's presence on the premises, and so long as the premises in question did not reasonably appear to be intended to be open to members of the public;
(5) Whenever used by a carrier of passengers or the carrier's authorized agent or servant, or other person assisting them at their request in expelling from a carriage, railway car, vessel, or other vehicle, a passenger who refuses to obey a lawful and reasonable regulation prescribed for the conduct of passengers, if such vehicle has first been stopped and the force used is not more than is necessary to expel the offender with reasonable regard to the offender's personal safety;
(6) Whenever used by any person to prevent a mentally ill, mentally incompetent, or mentally disabled person from committing an act dangerous to any person, or in enforcing necessary restraint for the protection or restoration to health of the person, during such period only as is necessary to obtain legal authority for the restraint or custody of the person.

RCW 9A.36.031
Assault in the third degree.
(1) A person is guilty of assault in the third degree if he or she, under circumstances not amounting to assault in the first or second degree:
(a) With intent to prevent or resist the execution of any lawful process or mandate of any court officer or the lawful apprehension or detention of himself, herself, or another person, assaults another; or
(b) Assaults a person employed as a transit operator or driver, the immediate supervisor of a transit operator or driver, a mechanic, or a security officer, by a public or private transit company or a contracted transit service provider, while that person is performing his or her official duties at the time of the assault; or
(c) Assaults a school bus driver, the immediate supervisor of a driver, a mechanic, or a security officer, employed by a school district transportation service or a private company under contract for transportation services with a school district, while the person is performing his or her official duties at the time of the assault; or
(d) With criminal negligence, causes bodily harm to another person by means of a weapon or other instrument or thing likely to produce bodily harm; or
(e) Assaults a firefighter or other employee of a fire department, county fire marshal's office, county fire prevention bureau, or fire protection district who was performing his or her official duties at the time of the assault; or
(f) With criminal negligence, causes bodily harm accompanied by substantial pain that extends for a period sufficient to cause considerable suffering; or
(g) Assaults a law enforcement officer or other employee of a law enforcement agency who was performing his or her official duties at the time of the assault; or
(h) Assaults a peace officer with a projectile stun gun; or
(i) Assaults a nurse, physician, or health care provider who was performing his or her nursing or health care duties at the time of the assault. For purposes of this subsection: "Nurse" means a person licensed under chapter 18.79 RCW; "physician" means a person licensed under chapter 18.57 or 18.71 RCW; and "health care provider" means a person certified under chapter 18.71 or 18.73 RCW who performs emergency medical services or a person regulated under Title 18 RCW and employed by, or contracting with, a hospital licensed under chapter 70.41 RCW; or
(j) Assaults a judicial officer, court-related employee, county clerk, or county clerk's employee, while that person is performing his or her official duties at the time of the assault or as a result of that person's employment within the judicial system. For purposes of this subsection, "court-related employee" includes bailiffs, court reporters, judicial assistants, court managers, court managers' employees, and any other employee, regardless of title, who is engaged in equivalent functions; or
(k) Assaults a person located in a courtroom, jury room, judge's chamber, or any waiting area or corridor immediately adjacent to a courtroom, jury room, or judge's chamber. This section shall apply only: (i) During the times when a courtroom, jury room, or judge's chamber is being used for judicial purposes during court proceedings; and (ii) if signage was posted in compliance with RCW 2.28.200 at the time of the assault.
(2) Assault in the third degree is a class C felony.

Coercion.
(1) A person is guilty of coercion if by use of a threat he or she compels or induces a person to engage in conduct which the latter has a legal right to abstain from, or to abstain from conduct which he or she has a legal right to engage in.
(2) "Threat" as used in this section means:
(a) To communicate, directly or indirectly, the intent immediately to use force against any person who is present at the time; or
(b) Threats as defined in *RCW 9A.04.110(27) (a), (b), or (c).
(3) Coercion is a gross misdemeanor.