Published
In August 2015, the news was a first: Regal, the country’s biggest theater chain at the time, would begin inspecting bags. The searches that still arrive (does Regal check bags, what size, can I bring a backpack) deserve the durable version of the answer, plus the origin story behind that first policy.
The policy, in practice
Regal’s posted policy reserves the right to inspect any bag brought into its theaters, which is a different thing from a promise to inspect every bag, and the difference explains the inconsistency people report. In practice the checks concentrate where risk math says: opening weekends of event films, premium-format screenings, urban flagship locations. The most consistently enforced element is size: bags beyond roughly the shoebox class (the commonly posted figure is 12x12x6 inches) face restriction or refusal, with standing exceptions for medical equipment and diaper bags. A small purse on a Tuesday matinee will usually pass unexamined; a backpack at a Friday premiere is the case the policy was written for.
Where the policy came from
The summer of 2015 put theater security on the national front page twice in three weeks: the Lafayette, Louisiana shooting in July, and an attack in Antioch, Tennessee days later. Regal’s response, announced that August, made it the first major chain to post inspection language, ahead of an industry that followed with nearly identical policies over the next few years. The move drew the predictable double criticism (security theater to some, insufficient to others), and a decade on it reads as the moment American moviegoing quietly adopted the venue-security norms concerts and stadiums already had.
The durable advice
Policies drift, wording updates, enforcement waxes with the news cycle, so the answer built to last is behavioral rather than legalistic. Assume any large chain can inspect; pack the small bag, not the backpack; keep medical needs in their own visibly-medical bag; add five minutes on event nights. And check the chain’s own posted policy page for the current size figure before an edge-case visit, because the number on any third-party page, this one included, describes the policy’s history more reliably than its present. That honesty is the house style here: this site keeps files on how claims get verified, and a security policy is a claim like any other — true as of its last check, and dated the moment after.