If he is living with the mother and being destructive then you would need to evict the mother, since she is your tenant.
Oregon law allows termination and filing of a forcible detainer action if a party allowed on the property by the tenant is causing a destruction of the premises.
Here is the statute:
2011 Oregon Revised Statutes
ORS Volume 3, Chapters 90 - 130
ORS Chapter 90
90.396 Acts or omissions justifying termination 24 hours after notice.
Universal Citation: OR Rev Stat § 90.396 (through Leg Sess 2011)
(1) Except as provided in subsection (2) of this section, after at least 24 hours written notice specifying the acts and omissions constituting the cause and specifying the date and time of the termination, the landlord may terminate the rental agreement and take possession as provided in ORS 105.105 to 105.168, if:
(a) The tenant, someone in the tenant s control or the tenant s pet seriously threatens to inflict substantial personal injury, or inflicts any substantial personal injury, upon a person on the premises other than the tenant;
(b) The tenant or someone in the tenant s control recklessly endangers a person on the premises other than the tenant by creating a serious risk of substantial personal injury;
(c) The tenant, someone in the tenant s control or the tenant s pet inflicts any substantial personal injury upon a neighbor living in the immediate vicinity of the premises;
(d) The tenant or someone in the tenant s control intentionally inflicts any substantial damage to the premises or the tenant s pet inflicts substantial damage to the premises on more than one occasion;
(e)(A) The tenant intentionally provided substantial false information on the application for the tenancy within the past year;
(B) The false information was with regard to a criminal conviction of the tenant that would have been material to the landlord s acceptance of the application; and
(C) The landlord terminates the rental agreement within 30 days after discovering the falsity of the information; or
(f) The tenant, someone in the tenant s control or the tenant s pet commits any act that is outrageous in the extreme, on the premises or in the immediate vicinity of the premises. For purposes of this paragraph, an act is outrageous in the extreme if the act is not described in paragraphs (a) to (e) of this subsection, but is similar in degree and is one that a reasonable person in that community would consider to be so offensive as to warrant termination of the tenancy within 24 hours, considering the seriousness of the act or the risk to others. An act that is outrageous in the extreme is more extreme or serious than an act that warrants a 30-day termination under ORS 90.392. Acts that are outrageous in the extreme include, but are not limited to, the following acts by a person:
(A) Prostitution, patronizing a prostitute or promoting prostitution, as described in ORS 167.007, 167.008 and 167.012;
(B) Manufacture, delivery or possession of a controlled substance, as described in ORS 475.005, but not including:
(i) The medical use of marijuana in compliance with ORS 475.300 to 475.346;
(ii) Possession of, or delivery for no consideration of, less than one avoirdupois ounce of marijuana as described in ORS 475.860 (3) or 475.864 (3); or
(iii) Possession of prescription drugs;
(C) Intimidation, as described in ORS 166.155 and 166.165; or
(D) Burglary as described in ORS 164.215 and 164.225.
(2) If the cause for a termination notice given pursuant to subsection (1) of this section is based upon the acts of the tenant s pet, the tenant may cure the cause and avoid termination of the tenancy by removing the pet from the premises prior to the end of the notice period. The notice must describe the right of the tenant to cure the cause. If the tenant returns the pet to the premises at any time after having cured the violation, the landlord, after at least 24 hours written notice specifying the subsequent presence of the offending pet, may terminate the rental agreement and take possession as provided in ORS 105.105 to 105.168. The tenant does not have a right to cure this subsequent violation.
(3) For purposes of subsection (1) of this section, someone is in the tenant s control if that person enters or remains on the premises with the tenant s permission or consent after the tenant reasonably knows or should know of that person s act or likelihood to commit any act of the type described in subsection (1) of this section.
(4) An act can be proven to be outrageous in the extreme even if the act is one that does not violate a criminal statute. Notwithstanding the references to criminal statutes in subsection (1)(f) of this section, the landlord s burden of proof in an action for possession under subsection (1) of this section is the civil standard of proof by a preponderance of the evidence.
(5) If a good faith effort by a landlord to terminate the tenancy under subsection (1)(f) of this section and to recover possession of the rental unit under ORS 105.105 to 105.168 fails by decision of the court, the landlord may not be found in violation of any state statute or local ordinance requiring the landlord to remove that tenant upon threat of fine, abatement or forfeiture as long as the landlord continues to make a good faith effort to terminate the tenancy. [2005 c.391 9; 2007 c.71 23; 2011 c.151 5]
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