Justice Souter, joined by Justices Stevens and Ginsburg, and joined by Justice Breyer as to the procedural discussion in Part II, maintained that Aguilar and Ball drew a sound constitutional line. In his view, publicly funded teachers who teach core subjects within religious schools assume responsibilities the schools themselves would otherwise bear, thereby directly subsidizing the schools’ religious missions and creating an apparent partnership between church and state.
He argued that the majority overstated the significance of Zobrest. A sign-language interpreter merely transmits what others say for one student and is constrained by professional duties of accurate translation. A teacher or counselor, by contrast, exercises substantial discretion and may reinforce a religious school’s pervasive sectarian environment. Thus, Zobrest did not reject the concerns about indoctrination or symbolic endorsement identified in Aguilar and Ball.
Justice Souter also distinguished Witters and Zobrest as cases of limited assistance flowing to individual beneficiaries through genuinely private choices. New York City’s Title I program, in contrast, served thousands of students in religious schools and provided systematic instruction in central educational subjects. In his view, this arrangement relieved religious schools of expenses they otherwise would incur and freed their resources for religious purposes.
Neutral eligibility criteria did not cure the constitutional defect, according to Justice Souter. Evenhandedness is necessary, but it is not sufficient when the actual effect of a program is substantial public support for religious institutions or a public appearance that government has endorsed their religious mission.
He further contended that the practical burdens caused by Aguilar were foreseen from the outset. Constitutional boundaries may produce regrettable costs and inconvenience, but those consequences did not justify erasing what he regarded as a principled and necessary line between on-premises and off-premises public instruction.