Strawbridge / Deveaux rule

a corporation aggregate, composed of citizens of one state, might sue a citizen of another state in the Circuit Courts of the United States; that is, they in effect decided, that although the artificial being, a corporation aggregate, was not a citizen, as such, and therefore could not sue in the Courts of the United States, as such, yet the Court would look beyond the mere corporate character, to the individuals of whom it was composed; and if they were citizens of a different state from the party sued, they were competent to sue in the Courts of the United States. But still, upon the principle of Strawbridge vs. Curtis, all the corporators must be citizens of a different state from the party sued.