James Clark McReynolds,
Mountain States Power Company v…
“ Obviously, also, the amendment relied upon has no application unless there is 'a plain, speedy and efficient remedy' in the state courts. And we cannot conclude that such remedy exists where, as here, a state statute definitely denying it has not been authoritatively condemned. In the circumstances it is impossible to know what position the courts of the State would take. A 'plain, speedy, and efficient remedy' cannot be predicated upon the problematical outcome of future consideration. ”
