ms. sridharan. ms. sridharan: mr. chief justice, and may it please the court: the epa set out to address the contributions of 23 upwind states to downwind air pollution through a single federal plan, but, as commenters predicted and before the plan became final, the legal predicates for the feder pn, that is, the state plan disapprovals, came under fire in courts all around the country. the specter of lesser partipion in the federal plan revealed yet another problem. the epa's choice of method, that is, selecting a single cost threshold and applying it uniformly across all 23 states tostablish emissions limits, has consequences; namely, the math doesn't work when the inputs don't match the outputs. with the sip disapprovals in flux and the epa's methodolog quing full participation, the epa had an obligation to considerhahappens to the federal plan when one or more states drop out, that is, when thints, 23 states, don't match the outputs, now the 11 states that remain in the plan. itfailure has become consequential. th