Quote from the Oregon Law books
Oregon law prohibits anyone, except a parent or legal guardian,
from providing alcohol to a minor or juvenile. A minor is any
person under the age of 21 and a juvenile is any person under
the age of 18. Parents or guardians may legally provide alcohol to
their minor child or ward and only in a private residence when
accompanying their minor child. A parent cannot transfer this
responsibility to another adult or provide alcohol in a public place. If
you allow your property and/or home to be used for a party where
minors, other than your minor child(ren), consume alcohol in your
presence, you may have to forfeit property and may be issued a
criminal citation.