Reverend Darnell Potter is a rather loudmouthed but charismatic and shrewd preacher who considers himself the main community leader for the African American population of New York.
Potter often portrays himself as a protector against perceived police brutality by the NYPD and calls for restrictions on Frank Reagan's power. Although Potter clearly believes in the left-wing ideals he supports, there is a double edge to his sword: he is willing to use almost any means to achieve his ends: bribing witness testimonies, falsifying evidence, coercing confessions, using tragedy to propel his political influence. Frank sums him up in a single, cutting line: "One thing I can say about you, you're good at what you do- it's just a shame that what you do is so damn corrupt." Reverend Potter appears in several episodes of Seasons 4 and 5.
In episode 5.04, "Excessive Force", Potter capitalizes off a scene in which Danny was framed as a police attacker against an African-American shoplifter who deliberately injured himself trying to escape Danny; only one witness, the young child of illegal immigrants, saw the true incident, and Potter had taken the family into his protection so that the police could not threaten them with deportation, then encouraged the boy to change his testimony.
He offered Frank a deal in which he would remove the media and public pressure on the NYPD as long as Danny was fired. However, Danny and Maria, having discovered where Potter was keeping the witness and offered them protection from deportation in exchange for the real testimony. Frank revealed this at a summit with Reverend Potter, revealing that he could have him arrested for witness tampering. However, wishing to show him the NYPD is capable of chivalry, Frank agrees to let Potter off with a warning and allows him to save face with his congregation.
In season 7, Potter suffers a personal tragedy when his son is shot dead on his way home from high school. Although the conflict between him and the Reagans initially reaches its' boiling point- with Potter believing they are unwilling to provide justice for him out of desire for revenge, and Danny and Frank furious with his impulsive interference in the investigation- Danny ultimately finds the killer, who- in a case of tragic irony- turns out to be one of the troubled youths Potter helped foster. Frank shares a moment of empathy with Potter over this by revealing that his son Joe was killed by a corrupt cop.