The film opens as Los Angeles Police Department (LAPD) Officer Dave Brown (Harrelson) patrols the Rampart Division. Brown is a 24-year veteran of the force, who previously served in the Vietnam War. While training a new officer, he roughs up a suspect to find the location of a meth lab. After work, he goes home to his two daughters and two ex-wives, who are also sisters (Heche and Nixon). After dinner, he goes to a piano bar where he picks up a stranger and has a one night stand.
The next day, he is t-boned in his patrol car. When he checks on the driver who hit him, the driver flees from his car, hitting Brown with his door as he exits. When Brown catches the driver, he brutally beats him, and the assault is captured by a bystander. The video creates another controversy for the LAPD, which is already besieged by the Rampart scandal. The Assistant District Attorney (Weaver) urges Brown to simply retire. He refuses and outlines his defense. Over the course of the film, it is revealed that Brown studied law and failed the bar exam, but he remains extremely knowledgeable about case law.
Back at the piano bar, Brown picks up a lawyer named Linda (Wright), after first determining that she is not surveilling him. Later he meets with ex-cop Hartshorn (Beatty), who suggests that Brown was set up to distract from the Rampart scandal. As the LAPD exerts more pressure on Brown, he retains legal counsel. Soon after, his ex-wives ask him to leave their houses so that they can sell them. Brown meets again with Hartshorn and mentions his need for cash. Hartshorn tips him off to a high stakes card game happening later that night at the Crystal Market.
While Brown surveils the card game, it is knocked off by two armed men. Brown pursues the men. He kills one of them and lets the other go. He then stages the scene to make it look like he was shot at. He realizes that a homeless man nicknamed "General" (Foster) witnessed the whole thing from his wheelchair. As another investigation into Brown heats up, he goes to a hotel and blackmails the concierge into giving him a room by threatening to arrest the concierge for running a prostitution ring in the hotel. Next, he blackmails a pharmacist into giving him an assortment of drugs.
When he meets with Hartshorn to give him a cut of the money from the card game, Brown asks for the source of Hartshorn's tip about the game. He suspects that he was set up again. Hartshorn refuses to name his source. Brown then meets with General in a parking lot to make sure that he will not testify about witnessing the shooting. The next day, an investigator with the District Attorney, Kyle Timkins (Cube) surveils Brown, who confronts him. Brown insists that he is not a racist, merely a misanthrope.
Brown grows increasingly paranoid and reliant on drugs as the pressure on him mounts. When he meets with Hartshorn again, he pulls a gun and accuses Hartshorn of setting him up. The elderly man scuffles with Brown a little bit and then has a heart attack. Instead of calling an ambulance, Brown leaves him to die. Back at the hotel, Brown's two daughters drop off some dry cleaning at his room, and he confesses to his younger daughter that everything she has heard about him is true.
Brown summons Timkins to a meeting and tapes a confession in front of him. He admits that he has been a dirty cop, and that in 1987, he killed a business acquaintance. He justified the murder because he knew the man was a serial rapist, which is why he got away with the extrajudicial killing. Timkins refuses the confession, insisting that he will arrest Brown for his most recent murder. The film ends with Brown revisiting his family and staring at his elder daughter on the front porch before disappearing into the night.
The marketing team behind Rampart posted controversial posters in several major U.S. cities before the film was released. They showed Harrelson’s character, Officer Dave Brown, beating a man with a sap. The posters stated "I Work For You" and were meant to look like street art posters. Oren Moverman, the director of Rampart, said one of the producers had been "searching for an image that would be thought-provoking and challenging, not an indictment of a cop but rather a communal approach to the idea of policing'; the idea that maybe when cops do bad things it’s more of a reflection of society and what it is willing to tolerate, rather than the fault of one bad apple or an institutional problem. If they work for us, could it be they are us?"
Woody Harrelson conducted several interviews to promote the film. In one interview with "The Playlist," Harrelson indicated "I had a period where I saw an early cut of the movie and didn't go for it, mainly because it was so different from the script and what we shot." Harrelson also lost significant weight to prepare for the role. During the same interview, he stated "I lost 30 pounds and a part of it was that I felt like he would have this relationship to food which is very similar to his relationship with women." Harrelson's take on the character was the following: "He can't really accept love, and if the food were representative of love. It's his inability to take that affection and nourishment." He went on to say about the character he played, "I would say if one emotion that is most at play with Dave Brown it would be paranoia. So that emotion was kind of with me quite a bit during the filming."
An attempt to market the film via the social news website Reddit went "horribly wrong" according to Forbes. Harrelson agreed to answer questions in an AMA (Ask Me Anything) session on Reddit's massively popular IAmA subreddit, where notable people engage in Q&A sessions with the Reddit community. Redditors were disappointed by his answers and his apparent misunderstanding of the format, with some vowing to "boycott the flick". CNET characterized one of Harrelson's responses as "sheer oozing, all-about-me-ism". Josh Feldman with MediaIte shared the following perspective: "a proxy for the actor basically gave vague answers to half of the questions and in-no-way subtle plugs for his upcoming movie Rampart to the other half. It was a public relations nightmare, and while it certainly raised awareness about the movie, it definitely backfired." Feldman went on to say about the incident, "it came across as robotic and represented an inability to connect with people when it should have been insanely easy to do so." Feldman summarized the lesson learned by stating the following, "When you’re doing an AMA on Reddit, you drop the act and engage with real people. Some will be fans, some won’t, but if you’re just honest and it doesn’t seem like your answers have been planned out, people will respect you for it."
Rampart received generally positive reviews and has a rating of 74% on Rotten Tomatoes based on 139 reviews with an average rating of 6.6 out of 10. The sites consensus was that "Rampart sends viewers plummeting into a nihilistic hell of its protagonist's creation, yet Woody Harrelson's performance in the central role is too magnetic to dismiss". The film also has a score of 70 on Metacritic based on 35 reviews. Roger Ebert gave the film four stars out of four and praised Harrelson's performance, writing "Harrelson is an ideal actor for the role. Especially in tensely wound-up movies like this, he implies that he's looking at everything and then watching himself looking."
Despite the positive critical reception, Rampart was a box office bomb, opening at #47 and earning only $60,446 on its opening weekend across 5 theatres in North America. It ended up making just $972,512 domestically and $595,393 elsewhere across 106 theaters for a total of $1,567,905 against an estimated $12 million budget. In addition, total domestic video sales were equal to $2,150,130.African American Film Critics Association Award for Best Actor
Nominated – Independent Spirit Award for Best Male Lead
Nominated – Satellite Award for Best Actor in a Motion Picture