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It is considered invasion of privacy and also illegal electronic surveillance to invade another person's home without a warrant, even with infrared cameras. If law enforcement will not take action, you still have the right to file a civil suit against them for invasion of privacy and also for them essentially trespassing into your home without a warrant and seek money damages and a restraining order prohibiting them from continuing the conduct.
At this point, if law enforcement will not charge them under the peeping Tom statute or stalking statute, then you have to file suit in civil court
The following would apply in WA:
9.70.110 Peeping Toms.
1. “Building” shall have the same meaning as in RCW 9A.04.110(5) as now or hereafter amended. Each room shall constitute a separate building. Restrooms, locker rooms and bedrooms are specifically included in this definition.
2. “Fully clothed” means having a person’s genitals, underclothing or a woman’s breasts covered. A person using a toilet or a urinal or wrapped in a towel is not fully clothed.
3. “Curtilage” shall be within ten feet from the exterior of a wall of any building, regardless of whether the premises are enclosed.
B. It is unlawful for any person to enter or remain in or upon the curtilage of a building or premises of another for the purposes of observing, photographing, videotaping or filming another person, under circumstances where the other person has a reasonable expectation of privacy and may not be fully clothed.
C. Violation of this section shall be a gross misdemeanor
. (Ord. 2007-38 § 8, 2007)
(1) A person commits the crime of stalking if, without lawful authority and under circumstances not amounting to a felony attempt of another crime:
(a) He or she intentionally and repeatedly harasses or repeatedly follows another person; and
(b) The person being harassed or followed is placed in fear that the stalker intends to injure the person, another person, or property of the person or of another person. The feeling of fear must be one that a reasonable person in the same situation would experience under all the circumstances; and
(c) The stalker either:
(i) Intends to frighten, intimidate, or harass the person; or
(ii) Knows or reasonably should know that the person is afraid, intimidated, or harassed even if the stalker did not intend to place the person in fear or intimidate or harass the person.
(2)(a) It is not a defense to the crime of stalking under subsection (1)(c)(i) of this section that the stalker was not given actual notice that the person did not want the stalker to contact or follow the person; and
(b) It is not a defense to the crime of stalking under subsection (1)(c)(ii) of this section that the stalker did not intend to frighten, intimidate, or harass the person.
(3) It shall be a defense to the crime of stalking that the defendant is a licensed private investigator acting within the capacity of his or her license as provided by chapter 18.165 RCW.
(4) Attempts to contact or follow the person after being given actual notice that the person does not want to be contacted or followed constitutes prima facie evidence that the stalker intends to intimidate or harass the person. "Contact" includes, in addition to any other form of contact or communication, the sending of an electronic communication to the person.
(5)(a) Except as provided in (b) of this subsection, a person who stalks another person is guilty of a gross misdemeanor.
(b) A person who stalks another is guilty of a class B felony if any of the following applies: (i) The stalker has previously been convicted in this state or any other state of any crime of harassment, as defined in RCW 9A.46.060, of the same victim or members of the victim's family or household or any person specifically named in a protective order; (ii) the stalking violates any protective order protecting the person being stalked; (iii) the stalker has previously been convicted of a gross misdemeanor or felony stalking offense under this section for stalking another person; (iv) the stalker was armed with a deadly weapon, as defined in RCW 9.94A.825, while stalking the person; (v)(A) the stalker's victim is or was a law enforcement officer; judge; juror; attorney; victim advocate; legislator; community corrections' officer; an employee, contract staff person, or volunteer of a correctional agency; court employee, court clerk, or courthouse facilitator; or an employee of the child protective, child welfare, or adult protective services division within the department of social and health services; and (B) the stalker stalked the victim to retaliate against the victim for an act the victim performed during the course of official duties or to influence the victim's performance of official duties; or (vi) the stalker's victim is a current, former, or prospective witness in an adjudicative proceeding, and the stalker stalked the victim to retaliate against the victim as a result of the victim's testimony or potential testimony.
(6) As used in this section:
(a) "Correctional agency" means a person working for the department of natural resources in a correctional setting or any state, county, or municipally operated agency with the authority to direct the release of a person serving a sentence
or term of confinement and includes but is not limited to the department of corrections, the indeterminate sentence review board, and the department of social and health services.
(b) "Follows" means deliberately maintaining visual or physical proximity to a specific person over a period of time. A finding that the alleged stalker repeatedly and deliberately appears at the person's home, school, place of employment, business, or any other location to maintain visual or physical proximity to the person is sufficient to find that the alleged stalker follows the person. It is not necessary to establish that the alleged stalker follows the person while in transit from one location to another.
(c) "Harasses" means unlawful harassment as defined in RCW 10.14.020.
(d) "Protective order" means any temporary or permanent court order prohibiting or limiting violence against, harassment of, contact or communication with, or physical proximity to another person.
(e) "Repeatedly" means on two or more separate occasions.