In Oregon, the only time its legal to use deadly force is when you are IN IMMINENT FEAR OF BODILY HARM.
I had a long discussion with an off-duty cop about this one time at a bar. I imagine the situation is similar in Washington.
One time whilst living in NW Portland I awoke to a woman screaming "Help me" outside my window. I jumped out of bed and ran outside, squinting across the street (I was nearsighted but LASIK corrected this) and saw a guy dragging this woman down the street in a hammerlock. I ran back inside my apartment grabbed my gun and ran back outside. I was in the middle of the street, about 40 feet away from this couple when I shouted "Let her go" and chambered a round in my 9mm. His hands went in the air and the woman took off running down the street. The guy yelled "whoa dude, she's my girlfriend." At this point I realized I still had not grabbed my glasses and was squinting at his blurry figure. I also realized there was about 10 other people standing around watching me pointing a gun at this loser. I decided it was time for me to go back inside.
Sucks being inside on such a nice day.