legislative and executive branches" (Klostermann v Cuomo, 61 NY2d 525, 541 [1984]). Deference to the Legislature is especially necessary where it is the State's budget plan that is being questioned. Devising a{**8 NY3d at 29} state budget is a prerogative of the Legislature and Executive; the Judiciary should not usurp this power. The legislative and executive branches of government are in a far better position than the Judiciary to determine funding needs throughout the state and priorities for the allocation of the State's resources. We have therefore spoken of the "formidable burden" of proof imposed on "one who attacks the budget plan" (Wein v Carey, 41 NY2d 498, 505 [1977]). Indeed, the burden is "realistically, impossible as to some categories of estimates. But there are some estimates that could be demonstrated on their face to be unreasonable. An extreme example would be a tripling of the estimates of personal income tax revenue, without a change in the tax rate, in a period in which the economy appears to be on a plateau or in decline." (Id.) The illustrations we gave in Wein v Carey, while extreme, were meant to show how patently irrational a state financing plan must be, before judicial deference will give way. Judicial intervention in the state budget "may be invoked only in the narrowest of instances" (id.). When we remitted in CFE II, we did so in order that Supreme Court would [*10]determine, when our deadline had passed, whether the State had implemented the reforms we requiredlegislation that would ensure that New York City schools have the resources necessary for providing the opportunity for a sound basic education and that would ensure accountability. CFE II called for the State to present evidence of its reforms, both predating CFE II (see 100 NY2d at 927) and following CFE II, and for Supreme Court to determine whether they satisfied our directives. In light of our language in CFE II and our jurisprudence as a whole concerning deference to the Legislature in matters of policymaking, it was incumbent upon Supreme Court to begin by making a finding as to whether the State's estimate of the cost of providing a sound basic education in New York City was a reasonable estimate. Then the court should have proceeded to determine whether the state plan, as of July 30, 2004, incorporated that sound basic education expenditure in its proposed budget and would, if enacted, ensure a system of accountability. Supreme Court should not have provided a panel of referees with a mandate to make recommendations as between compliance{**8 NY3d at 30} proposalsthe State's, the plaintiffs', the City's, the Regents'. The State, not Supreme Court, was ordered to ascertain the cost of a sound basic education in New York City. IV. We do not believe that Governor Pataki's proposed State Education Reform Plan was unreasonable. In particular, we do not find irrational the Governor's acceptance of the Board of Regents approach to identifying successful schools, the S & P weightings for students with special needs and the cost-effectiveness filter (2004 Extraordinary Session NY Senate Bill S 1-A,