Slaughterhouse still important b/c 14th am. rts. still require state action, while P&Is of federal citizenship do not require state action.
1.    dp requires state action (14th am. requires state action per Civil Rts. Cases)
2.    ep requires state action
3.    but P&Is of federal citizenship do not require state action
4.    P&Is of state citizenship require state action by their definition