A Client (C) comes to his Lawyer (L), asking for legal advice.
C: My neighbor owes me $500 and doesn't want to return it. Can I somehow sue him to get the money back?
L: Sure but you will need written proof that he owes you. Do you have it?
C: I'm afraid not. It was just a verbal agreement.
L: Then write him a letter, demanding that he immediately pays you back $1000.
C: But he only owes me $500.
L: That's exactly what his response will be. That'll serve as your written proof!