§ 143A.004.Applicability of Chapter

Four applicability limits, and the third is the one that names the defendants.

Subsection (a): the chapter applies only to a user who resides in this state, does business in this state, or shares or receives expression in this state.

Subsection (b): only to expression that is shared or received in this state.

Subsection (c) sets the size threshold: only to a platform that functionally has more than 50 million active users in the United States in a calendar month.

That confines the chapter to the largest platforms — a handful of companies — and reflects the chapter’s theory, which is about the dominant channels of public communication rather than about websites generally.

"Functionally" is doing quiet work, and appears aimed at preventing a platform arguing its way under the threshold by how it counts users.

Subsection (d) is a savings clause of an unusual kind: the chapter applies to the maximum extent permitted by the United States Constitution and the laws of the United States but no further.

The repetition is the point. It instructs a court to read the chapter as reaching as far as it lawfully can, and as stopping there — which is a direction to sever rather than strike down, and an acknowledgement that the constitutional boundary was uncertain when the chapter was drafted.

That uncertainty was well founded. The chapter has been litigated continuously since 2021, and the question of how far a state may regulate platform moderation has been before the United States Supreme Court.