This series is the result of a yearlong examination of high-arrest practices in many towns across Pennsylvania, including several in the suburbs of Philadelphia.

The analysis focused on enforcement of charges such as disorderly conduct, jaywalking and loitering.

Unlike serious felonies and violent crimes, the enforcement of these minor-offenses laws is usually a matter of police discretion. Thus, criminologists say, they can offer a way to analyze how different departments approach their jobs.

Using FBI arrest statistics dating to 1994, in conjunction with census population estimates, The Inquirer calculated rates for crimes for hundreds of towns across the state.

In several towns in the region, The Inquirer found, police made arrests on low-level statutes at rates among the highest in the country. Minorities were arrested at rates far exceeding their numbers in the population.

To bolster this analysis, The Inquirer examined seven years of computerized Pennsylvania court records, and contacted some of those arrested. Many alleged that they were victims of racial profiling.

Reporters also used Justice Department data showing the racial makeup of more than 2,000 police departments. They questioned constitutional law experts, judges, police officials and criminologists.

Dozens of officers, both active and retired, were interviewed. Reporters went on ride-alongs with police in order to understand their views of the law-enforcement problems in their communities.

Ultimately, the investigation disclosed patterns of aggressive enforcement in the region often supported by home-grown, locally written ordinances - many of them apparently unconstitutional, according to legal experts.