<P> According to a 2001 study of crime trends in New York City by Kelling and William Sousa, rates of both petty and serious crime fell significantly after the aforementioned policies were implemented . Furthermore, crime continued to decline for the following ten years . Such declines suggested that policies based on the Broken Windows Theory were effective . </P> <P> However, other studies do not find a cause and effect relationship between the adoption of such policies and decreases in crime . The decrease may have been part of a broader trend across the United States . Other cities also experienced less crime, even though they had different police policies . Other factors, such as the 39% drop in New York City's unemployment rate, could also explain the decrease reported by Kelling and Sousa . </P> <P> A 2017 study found that when the New York Police Department (NYPD) stopped aggressively enforcing minor legal statutes in late 2014 and early 2015 that "civilian complaints of major crimes (such as burglary, felony assault and grand larceny) decreased during and shortly after sharp reductions in proactive policing . The results challenge prevailing scholarship as well as conventional wisdom on authority and legal compliance, as they imply that aggressively enforcing minor legal statutes incites more severe criminal acts ." </P> <P> Albuquerque, New Mexico, instituted the Safe Streets Program in the late 1990s based on the Broken Windows Theory . Operating under the theory that American Westerners use roadways much in the same way that American Easterners use subways, the developers of the program reasoned that lawlessness on the roadways had much the same effect as it did on the New York City Subway . Effects of the program were reviewed by the US National Highway Traffic Safety Administration (NHTSA) and were published in a case study . </P>

The broken windows theory views crime as highly unpredictable