They don't have one. Seriously--you can return something you bought at Nordstrom's four years ago and they have to accept it. They'll give you a hard time, might ask you never to come back--but they will accept it.
Even if the item is worn, they will accept it. When I worked there, a lot of people would bring back items they washed and it shrank...we had to accept it.
Like I said though, they use a lot of manipulative skills to force you not to return it, but the policy for Nordstroms is that there is no policy--according to them, that's the best customer service.
I wouldn't abuse this however, because they do check---if you return more then $5,000 (i believe) worth of merch consistently and with a bad excuse for returning the item, you will get a letter in the mail asking you never to shop at Nordstroms.
Myself and I, a former employee for over 5 years.