Many of the immigrants have come here to the United States to escape problems in their own countries. Explain the importance of the role of police officers in protecting such freedoms. How should they treat people such as new immigrants? Explain the importance of the role of police personnel In the New York City Police Department (NYPD) in protecting such freedoms. How do police officers in the NYPD treat people such as new immigrants?

Police officers are law enforcement officials. They exist to protect the citizenry and to enforce laws. Those laws, with occasional notable exceptions (notable because the United States Supreme Court eventually ruled them unconstitutional and thereby illegitimate), have their conceptual origins in the Constitution of the United States, especially the first ten amendments to the Constitution, the Bill of Rights. Immigrants fleeing persecution for their religious beliefs, political beliefs, or for their ethnicity come to the United States because of the freedoms guaranteed to the citizens of this country under the provisions of the Constitution. 
The law enforcement officers who collectively comprise the New York City Police Department are, as with all law enforcement officers in the United States, sworn to uphold the laws of the city they represent. Those laws must be compliant with the Constitution of the United States and with all United States Supreme Court decisions determining the constitutionality of locally-enforced statutes. As such, the New York Police Department must enforce laws against the inappropriate use of violence and against discrimination of people on the basis of their race, ethnicity, religion and sexual orientation. 
"New immigrants" are by definition not citizens of the United States. They are, however, people. As long as such individuals do not violate the laws of the city or state in which they reside and, in principle, as long as they are in the United States legally, they deserve the full protection of the police. Indeed, even those who enter the United States illegally deserve the protection of the police against prejudicial conduct on the part of others. The question of whether illegal immigrants should be afforded the freedoms and protections guaranteed citizens by the Constitution is complex, but human decency suggests that such individuals should be treated humanely and according to the laws that pertain to the citizenry as a whole.
New York City is home to over eight million people. It is a dense urban environment in which the slightest spark, such as a questionable police shooting or even an electrical outage, can result in mass upheaval among the populace. In other words, wide-scale rioting can break out under the right circumstances quite easily. New York is also an enormously diverse city in terms of the multitude of ethnicities present there. Historically, it has been the main entryway for waves of immigrants from Europe and, increasingly, from other, often war-torn regions. Police officers have to be carefully trained to deal with a very wide range of people speaking an equally wide range of languages. Encounters often occur within newly-established ethnic enclaves of recently resettled immigrants who have yet to assimilate. Inevitably, problems arise between the police and individuals and groups within such communities. 
There is a strong push across much of the United States to advance the cause of diversity in virtually every category of human endeavor. Sometimes, this push reaches ludicrous extremes. In the case of policing, however, diversity is essential. Immigrants fleeing persecution bring with them a long-held fear of police because of their experiences in their native countries. Chinese and South Vietnamese immigrants from earlier periods, for example, distrusted police officers because of problems of systemic corruption among police in their native countries. Policing communities of such emigres, therefore, demands a level of cultural awareness among the police that can only come through protracted educational processes and, most importantly, by the recruitment of police officer candidates from among emigre communities. Police officers from this latter category speak the language and understand the customs of the communities from which they were recruited.