From the San Antonio Court of Appeals’ opinion in Ex Parte Thompson (PDF), which is before the Texas Court of Criminal Appeals on discretionary review (and will be argued tomorrow morning by Don Flanary III of San Antonio and Eugene Volokh of L.A.):
[W]e hold the plain language of the subsection 21.15(b)(1) does not “limit” or “restrict” the substantive content of photographs—in other words, it does not favor one type of photograph over another. See Turner, 512 U.S. at 642. Rather, the statute limits speech by imposing time, place, and manner restrictions that are unrelated to content. See Clark, 468 U.S. at 293. Accordingly, we hold subsection 21.15(b)(1) regulates speech in a content-neutral manner, requiring intermediate scrutiny. See id.
Here’s the gist of Texas Penal Code Section 21.15(b)(1):
A person commits an offense if the person photographs or by videotape or other electronic means records, broadcasts, or transmits a visual image of another at a location that is not a bathroom or private dressing room….
The San Antonio Court got the question of whether 21.15 is content-based or content-neutral wrong. (It matters because a content-based statute has to pass stricter scrutiny than a content-neutral one; the San Antonio Court found that 21.15 did not even pass the lesser scrutiny.)
If it is necessary to look at the content of the speech in question to decide if the speaker violated the law, then the regulation is content-based. Gresham v. Peterson, 225 F.3d 899, 905 (7th Cir. 2000).
With Section 21.15, it is necessary to look at the content of the speech (the photograph): if it contains “a visual image of another,” that is, a picture of a person, it can infringe the statute; if it does not contain a picture of a person, it cannot.
For the convenience of courts of appeals for whom this concept might be too complex, I offer the Grumpy Cat Rule: If the statute favors images of grumpy cats over other images, its regulation of speech is content-based.