Lindsey — I think it’s worth noting that the judge’s ruling invoked not some grand constitutional principle, but the somewhat odd process that the state constitution requires for education funding.
The provisions the ruling rests upon (B and C) are here, and the ruling itself is here. (The arguments that the program is unconstitutional start on page 21; the pages are upside-down, so you’ll need to rotate the PDF.) It’s not a cut-and-dried legal issue, but the judge does make a reasonable case that “Minimum Foundation Program” funds — the source of voucher money — may not be given to private schools.