Brahmer — and several other school officials who have invited either Brown or Becker to speak — said the assemblies were not mandatory.

In Pierce, in northeast Nebraska, one student chose not to attend Brown’s talk.

ACLU Nebraska’s legal director Amy Miller said that doesn’t matter. Even if students are given an opt-out, an assembly during school hours that organizers “know to be religious” could violate the Constitution.

Josephine Potuto, a professor of constitutional law at the University of Nebraska College of Law, said there are “a lot of gradients” between what is and is not acceptable in a public school under the First Amendment.

She explained it this way: Because a World Religions class is taught as a subject, not as doctrine, that’s clearly acceptable. On the other side, she said, school-organized prayer is not permissible because “that forces children to profess to a certain belief they may not believe.”

The presentations by the two speakers, the law professor said, fall somewhere in the middle.

A judge, she said, would have to consider the facts involved if a lawsuit was brought. Among them: the age of students involved and the actual words used.