Chicago Bears fans reserve their venom for the visiting team. But after Sunday's season opener at Soldier Field against the Cincinnati Bengals, they may have a few not-nice things to say about Juan Gaytan's squad, too.

Mr. Gaytan's security firm,Monterrey Security Consultants Inc., is charged with guarding the stadium. As such, it's on the front lines of enforcing the NFL's new rules on what fans can bring into stadiums, imposed after April's deadly attack at the Boston Marathon.

The restrictions are much tougher: People entering Soldier Field are limited to carrying small, clear plastic bags; purses are limited to small clutches. Monterrey's staff will search the bags and wand fans to see if they're trying to smuggle in anything else. For $10, spectators can rent lockers to store their forbidden stuff, or have it confiscated as if they were trying to bring liquids through security at the airport.

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