Law enforcement agencies in the United States have relied on photo enforcement to decrease dangerous driving behaviors since the late 1990s. Redflex Traffic Systems introduced the nation's first photo enforcement program in Paradise Valley, Ariz. in 1997, which monitored speeding and red light incidents. The program continues to operate today.

Photo enforcement has been used internationally to improve roadway safety since the 1960s.

Photo enforcement is designed for use on roadways with a history of crashes or violations resulting from dangerous driving behaviors, such as red-light running, speeding or illegally passing a stopped school bus. It should be considered once all other safety options have been analyzed, implemented and/or optimized. For instance, prior to the installation of a photo enforcement system, intersections and roadways should be well designed from a safety standpoint, speed limits should be set to the appropriate level for the roadway and yellow-light timing should be reviewed. If the danger still exists after all appropriate safety options have been optimized, photo enforcement could help curb the problem.

The Insurance Institute for Highway Safety (IIHS) conducted one of the most comprehensive studies assessing the effectiveness of red light photo enforcement in 2011. It found a 24% reduction in fatalities across 14 cities with red light camera programs operating from 2004 to 2008. Had similar programs been operating in all large cities during that period, 815 deaths could have been prevented.

Every photo radar citation issued provides an opportunity for the driver to either pay the fine, request a hearing or if eligible attend traffic school. If the driver decides to request a hearing they have the opportunity to challenge the citation. Further, each citation mailed includes information on how to access the violation video, providing the driver with an opportunity to review the incident.

As determined by the United States Supreme Court there is no right to privacy on a public roadway. Consequently, the use of photo radar provides no foundation upon which to base a 4th Amendment challenge to unreasonable search and seizure or invasion of privacy. The constitutionality of photo enforcement has been repeatedly upheld by the courts of Arizona and the United States Supreme Court.

In most cases, photo enforcement systems are "cost neutral," which means the monies collected from citations originating from photo enforcement can fully fund the programs. Additionally, taxpayers do not front any costs for the system installation.

The primary goal of a photo enforcement system is to protect the safety of citizens who utilize the roadways. Since photo enforcement systems are intended to serve as deterrents, successful programs often see a reduction in citations (and therefore a reduction in the amount of money collected). A reduction in photo enforcement revenue is actually a sign the deterrent effort is working.

The local law enforcement agency is the only entity that can determine if a citation is warranted. Redflex provides officers with secure, comprehensive evidence packages that offer the situational awareness needed to assess whether a ticket should be issued.