This is a good question. Unfortunately, we do live in a world where race matters. People still make assumption of people based on how they look. This is even true of law enforcement. Let me give you a few ways in which this is done.
First, there is racial profiling. So, often times, the police target certain races more than others. More African-Americans are pulled over by the police and given a hard time. Last year, professor Gates from Harvard University was stopped going into his own home. This incident even made it to President Obama.
Second, in view of 911, many Muslims are also a target of race discrimination. Just last month, the New York City police department was called into question for monitoring Muslim students from many top college campuses. This has caused an uproar among Muslim Americans. In addition, there was a recent report saying that there are spies on our college campuses as well. This leads to more surveillance of Muslims and some Chinese students.
Finally, the whole Trevon Martin case shows racism. The very fact that Zimmerman was not arrested shows that something is broken.