Legal Question in Wills and Trusts in Oregon

It depends on what you mean by "co-owner." If the other co-owner was your spouse, then yes. If you were not married, the ownership would have to have been designated "with the right of survivorship." If it was not, then you do not automatically get full ownership. The one half owned by the deceased person may be subject to that person's estate. You should seek the help of an attorney to establish proper ownership.