Who are the persons liable on an instrument?

General Rule:

Only persons whose signatures appear on an instrument are liable thereon. (Sec. 18)

Exceptions:

1. Person signs in trade or assumed name (Sec. 18 [2]) – Party who signed must have intended to be bound by his signature.

2. Principal is liable if a duly authorized agent signs in his own behalf disclosing the name of the principal and adding words to show he is merely signing in a representative capacity. (Sec. 19) – Authority may be given orally or in writing (SPA, only an evidence of authority of an agent to third parties)

3. In case of forgery (Sec. 23)

4. Acceptor makes his acceptance of a bill on a separate paper (Sec. 134)

5. Person makes a written promise to accept the bill before it is drawn (Sec. 135)