What part?
That person is lucky that that caliper holds the pad in place, with some it'll spit the pad out causing more problems. Back when I worked at a car rental place a guy wore the inboard side of the rotor off, the pad ejected, the piston went into the vent and locked the tire sending him off the side of the freeway. He came in screaming about the dangerous car we gave him and said he was gonna sue. I pulled out his contract and handed it to the boss. I'd written the date and time of his phone call to complain about brake noise and I told him to bring the car in, about two weeks before the crash. I think the boss wound up making a deal with him to buy the car instead of paying for the damages.