New York City Mayor Bill de Blasio’s campaign to expand pre-kindergarten access may have hit some constitutional snags. Sectarian schools have been included in the push, and even though efforts have been made to protect the separation of church and state, there’s evidence those attempts are still falling short.Under a new de Blasio policy, sectarian schools can qualify to host publicly funded, day-long classes. It’s quite a potential windfall for the schools: According to the New York Times, they could receive up to $10,000 per student if selected for the program. That’s a lot of public funding for private, religious schools.

To give credit where it’s due, I’ll note that the mayor’s administration does seem to acknowledge there’s a potential First Amendment conflict looming. They recently informed schools that they couldn’t teach their religious texts as fact or display religious symbols in classrooms used by students in public classes. But that presents a problem for some schools, which until now haven’t been forced to toe this dodgy legal line. And in schools where religion and ritual are integrated into instruction, that demarcation might not be possible.

The fact that the city isn’t asking schools to completely erase religion from the classroom further complicates the matter. Although schools can’t teach religion as fact, or display symbols in certain areas, the city has attempted to make a nebulous distinction between dogma and culture. Cultural symbols, they say, are allowed.

The Orthodox Union’s Jeff Leb asked the Times, “Can you conduct a mock Passover Seder? Can you discuss the symbolism of the menorah for Hanukkah? Can you have a sukkah at the back of the school? Are these things cultural or religious?” His questions illustrate the difficulty (some would say the impossibility) of enforcing these distinctions.

And the problems don’t end there. Sectarian schools have been hosting public programs for years—but those programs tended to be half day, which somewhat mitigated any potential constitutional violation. Now, de Blasio wants schools to extend those programs for a full day, and that means there’s no easy cut-off separating secular and religious instruction.

Orthodox Jewish schools have already successfully petitioned for and been granted certain accommodations, like the right to hold their publicly funded classes on Sunday. They’re also requesting further exemptions that would allow them to hold shorter instructional periods—still on the public dime.

de Blasio doesn’t have a reputation for religious fundamentalism and there’s no evidence that his pre-k push is motivated by sectarian impulses. But whatever his motivations might actually be, the truth is that he’s pulled the city into some potentially dangerous territory.

Not only does this program funnel public funds directly to sectarian schools, it places the city in a precarious position by forcing it to determine which symbols and rituals are acceptable and which are not. Despite the city’s attempt to clarify First Amendment law to these schools, it’s a concern that some schools are already pushing for (and receiving) special accommodations. And, given the nature of the program, it’s almost inevitable that First Amendment violations will occur.

That’s a potential expense for the city and a distraction from the program’s primary goal, which is to educate children.

The mayor should be commended for his commitment to educating disadvantaged children. But it’s time for him to rethink his strategy.