On weekend nights, downtown Fullerton transforms from an eclectic array of eateries and trendy boutiques into party zone. As these food and drink establishments become nightclubs, swarms of 20-somethings converge on the area surrounding Harbor Boulevard and Commonwealth Avenue, known as the SOCO District. They cram into the club of their choice, barely able to move in some cases, much less dance. The Fullerton Police Department’s ECHO Unit is tasked with maintaining order in the popular area. One way involves making unannounced visits to some of downtown’s 50-plus restaurants and bars to ensure they aren’t exceeding their occupancy limits, which…