The U.S. Supreme Court is quite vigilant in enforcing its justiciability rules concerning standing to sue. For over half a century, however, the Supreme Court has reduced the rigor of its standing rules when a claim is lodged under the Establishment Clause of the First Amendment. The Court famously did so with respect to federal taxpayer standing in the venerable case of Flast v. Cohen, but in no instance other than claims invoking the Establishment Clause is federal or state taxpayer standing ever permitted. Less well known is the reduced rigor with which the Court has applied its standing rules when it comes to a plaintiff’s “unwanted exposure” to a religious symbol or other speech attributable to the government...