U.S. child-pornography statutes recklessness standard

Which U.S. courts have applied a reckless‑disregard mens rea to child pornography statutes and what were the facts of those cases?

A small but important body of U.S. case law and statutory interpretation shows courts reading a recklessness or “reckless‑disregard” standard into child‑pornography and adjacent statutes when the text...