Commissioner Raymond W. Kelly is the cop from central casting, possessed of a square jaw, swagger and charm, and a flinty willingness to challenge any critic. Of late, party and business leaders have tried to lure him into carrying the Republican banner in the 2013 mayoral derby.

Mr. Kelly has so far demurred. He acknowledges that the attention and favorable poll numbers are flattering. But he says he loves running the biggest municipal police force in the country.

No doubt he does.

Another cop, a cinder block of a man named Adhyl Polanco, also loves the New York Police Department. Or he did until he ran afoul of a body he describes as ever more consumed with writing nuisance tickets, executing dubious stop-and-frisks and arrests, and manipulating crime reports.

It’s also a department, he discovered, that squashes any hint of dissent.

Officer Polanco said his supervisors in the 41st Precinct in the Bronx instructed him to slap handcuffs on teenagers guilty of nothing more than a boisterous walk to school. They told him to change reports of felony burglaries and attempted murder to far less serious charges of trespass and reckless endangerment.