Police Academy 4: Citizens on Patrol is the fourth comedy film in the Police Academy series. It was released in 1987.
A group of Police Academy graduates are sent to train a group of newly recruited civilian officers. The original Police Academy cast reprise their roles in the film. Capt. Harris, not seen since the first installment, returns as the film's nemesis. In Police Academy 2 and 3, Capt. Mauser (played by Art Metrano) filled that role, but Metrano asked to be replaced for the remainder of the series after filming number 3. This was the last Police Academy Movie to feature Steve Guttenberg as Carey Mahoney. This film also stars a young David Spade, as well as a brief appearance from pro skateboarder Tony Hawk as Spade's double in the skateboarding scene.
Commandant Eric Lassard (George Gaynes) decides that the police force is overworked and understaffed, so he comes up with the idea of recruiting civilian volunteers to work side-by-side with his officers in a program called "Citizens On Patrol" (COP). Carey Mahoney (Steve Guttenberg) and his friends Moses Hightower (Bubba Smith), Larvell Jones (Michael Winslow), Eugene Tackleberry (David Graf), Zed (Bobcat Goldthwait), Sweetchuck (Tim Kazurinsky), Laverne Hooks (Marion Ramsey), and Debbie Callahan (Leslie Easterbrook) are in charge of training the civilians. The civilians include the enormous Tommy "House" Conklin (Tab Thacker), gung-ho senior citizen Lois Feldman (Billie Bird), Tackleberry's own father-in-law, and skateboarding delinquents Kyle (David Spade) and Arnie (Brian Backer).
Captain Thaddeus Harris (G. W. Bailey) believes "the concept of citizens doing police work is asinine" and is determined to see the COP program fail and take over Lassard's job at the academy. When Lassard leaves on an overseas conference, Harris, along with his right hand man Lt. Proctor (Lance Kinsey), are put in charge of the academy and Harris immediately plots to make the COP volunteers quit and leave the police work to the officers. The volunteers however do well in their training. Mrs. Feldman excels in firing Tackleberry's .44 Magnum and the two find a friendly bond in each other. In training for water safety and drowning victim rescue, Zed "rescues" a cadet but experiences a personal loss of his no longer functioning watch, and mourns the death of the cartoon character inside of it saying it was the last thing he ever stole before joining the academy. Through his loss Zed gains a love interest, Laura (Corinne Bohrer), a reporter/photographer who has come to the academy to view Lassard's COP program and takes a fancy to Zed. Unfortunately Harris ruins the moment and insults Zed and Laura, which causes Zed to replace Harris's deoderant with mace. In the next scene while Zed instructs the volunteers on the very important matter of how to correctly eat a donut, Harris is seen wearing a medical device suspending his arms in the air. Despite the pranks played upon him during the various training exercises the volunteers take, Harris is determined to make the Citizens on Patrol program fail.
Jones learns that volunteers House, Kyle, and Arnie believe themselves ready to go out and catch criminals, so Jones, Mahoney, Hightower, and Tackleberry play a prank on the boys to make them take their training more seriously. Later, after being yelled at again by Captain Harris and being called a disgrace, Zed is comforted again by Laura, who says she thinks he is perfect.
After several volunteers accidentally foil an undercover police sting, the Citizens on Patrol program is suspended, much to Harris's delight. While Harris gives a tour of his precinct, Proctor messes up and is tricked into releasing every inmate at the precinct 19 jail, including a team of ninjas, and special guest Randall "Tex" Cobb. After the criminals imprison Harris and his guests, they make their escape from the precinct only to run into Mrs. Feldman, who wastes no time informing the Lassard Academy.
When Lassard's officers hear of the jailbreak, the COP volunteers are dispatched along with the regular officers to catch the escaped felons. After stopping a robbery and a high speed air balloon chase, the felons are all recaptured. Meanwhile House, Kyle, and Arnie save Harris and Proctor from drowning in a river after the latters attempt (and fail) to participate in the chase, and Zed impresses his girlfriend Laura by saving Sweetchuck's life after they both fall out of a plane in mid-air. The several police chiefs who came to witness Lassard's program in action congratulate and compliment Lassard on his program and his officers.