Hold onto your butts: BART's new "seat hog" rule is here and it's ready to party. Or be enforced. Whatever.

Passed in April, the measure allows BART police to run criminal background checks on riders and issue citations to those taking up more than one seat on the frequently crowded trains. Although the new rules, which KRON 4 reports officially kicked off on September 1, only apply during weekday rush hour times, some worry that an expected increase in confrontations between BART police and passengers may lead to train delays and potential violence.

And one of those concerned happens to be the chief of BART police. “We’re not going to get out there and start arresting people and issuing lots of citations,” Chief Kenton Rainey told the BART board back in March. He was quick to point out, however, the reality of such a measure going into effect — "more train delays, conflicts with the homeless and possible use of force."

The San Francisco Business Times tells us that the ordinance will only be enforced Monday through Friday, from 6 a.m. to 10 a.m. and 3 p.m. to 7:30 p.m. Those found taking up more than one seat in violation of the ordinance will be issued warnings, fines, and potential jail time (for repeat offenders). Fines can go as high as $500.

Bag-encumbered riders need not freak yet — officials are going to mostly stick to warnings for the first month of the new measure. And for those concerned that this will just be another way for police to target the homeless, fear not: Rainey assured the Chronicle in June that his department will be an equal opportunity enforcer.

“It’s going to be applied equally to the person who puts a briefcase on a seat on a crowded train during the commute or a person who puts a gym bag on a seat, or the person who puts a suitcase on a seat, or the person who puts his feet on the seat and goes to sleep,” the chief explained. “We’re going to treat everyone the same.”

Here's hoping that everyone, including tourists heading to and from SFO, got the message.

Previously: Manspreaders Beware: BART 'Seat Hog' Ordinance Passes