Another recent example of motivating officers to make more DUI arrests (valid or otherwise), this from a Placer County (California) Sheriff's news bulletin:

Four Placer County Sheriffs received awards from Mothers Against Drunk Driving at the organization's annual statewide awards ceremony on April 9 at the Grand Sheraton in Sacramento. Last month, the local MADD chapter recognized the same deputies at a luncheon in Sacramento. The four deputies, Glen McNama, James Concannon, Robert Griggs and Douglas Bostian accounted for more than 120 arrests in 2004. McNama is a five-time winner. Griggs accounted for 10 percent of the sheriff's department total DUI arrests.

Again, no requirement of convictions — just arrests. These awards are career-boosters, of course, but making lots of DUI arrests can also be very lucrative: since most arrests are made on the evening shifts, officers usually get overtime pay to appear in court during the day to testify. Note: good arrests usually result in guilty pleas, not requiring the officer's presence in court; bad arrests more often go to trial — resulting in more overtime pay. So….