See how technology is linking guns used in crimes, helping investigators solve cases

Colombia has attempted to decrease murder and homicide rates by setting up curfews for teenagers, forcing bars to close earlier in the evening, and creating gun laws to prevent the carrying of weapons. As a result of this epidemiological, data-driven approach, along with other governmental factors, the homicide rate has decreased significantly in most of the cities in which it was implemented.

The California prison system is overwhelmed after adopting tough-on-crime laws with no improvement. New York adopted more tolerant policies and has decreased the state's crime rate and its prison population.

In Houston, TX, many individuals with mental illnesses cycled in and out of emergency care while arrested or incarcerated. Houston’s police department has decreased the number of incarcerated who have mental illness by opening a division to mental health called the Chronic Consumer Stabilization Unit. Now Milwaukee seeks to replicate Houston’s results.

Milwaukee County’s mental health system put more resources in expensive emergency care rather than invest in programs that offer continual care. As a result, Milwaukee County identifies nine solutions from other cities that have had success in repairing mental health systems. Solutions include the ending of reliance on emergency care, expand community support programs, change laws, and supportive housing.

The militarization of police forces in cases such as Ferguson, Missouri’s riots has led the state of Utah to question what can be done to prevent such an overuse of force from happening. Utah expanded upon a law passed by Democratic legislature in Maryland, which Utah’s ACLU reworked with some libertarians, to require the police to provide data about SWAT team usage. Utah’s success demonstrates that demilitarization bills passed with bipartisan support are not impossible.

Richmond, California ranked among the highest homicide rates in the country. The city created the Office of Neighborhood Safety to engage the community in the effort to curb gun violence and prevent homicides. ONS works directly with the young people who are at risk and have succeeded in reducing the homicide rate.

Rampant misconduct by judicial systems across the country brought to light a crippling practice of debtors' prisons—where disadvantaged individuals unable to pay fines and fees were continually and wrongfully imprisoned, creating a vicious cycle. The American Civil Liberties Union stepped in to work with governments and private companies to increase transparency, eliminate abuse, and reeducate law enforcement officials. The state of Ohio has emerged as a leader in reforming debtors' prisons, though there is still work to do.

Many offenders get out of jail owing hundreds or thousands of dollars in court and parole fees but face barriers to financing and job acquisition, sticking them in a punitive, vicious cycle of debt and arrest. A program called the Clapham Set, perhaps paired with conditional cash transfers - may be a solution, as it erases fees for felons who complete rehab and job training upon release.

A program in Philadelphia is pioneering new ways to treat the urban wounded. By seeing it as PTSD, and not pointing fingers, the city is using mental health tools to decrease violence and heal communities.

In Brooklyn's Crown Heights neighborhood, an organization called Save Our Streets Crown Heights (S.O.S.) is taking steps to disrupt violence. The organization is modeled after Chicago's violence interrupters, which employ people from the neighborhood to connect with those most at-risk and disrupt conflicts and retalitory violence.