First, police brutality affects you directly. Sooner or later you will be (if not already) the victim of an unconstitutional or illegal police action, such as a profile stop, random search, no-knock raid, frame-up, wrongful assault or shooting.
Second, because the police are increasingly targeting innocent young people, people of color, and dissidents under the hysteria generated by the "war on crime".
Third, because even if you are a white middle aged citizen, your life can be destroyed by the police at any time via frame-ups, asset forfeiture, or "accidental" shootings. For example, the government is using the precedents established by the war on drugs to go after conservative gun owners. Look at Waco.
Fourth, because the government rarely prosecutes law enforcement officers for killing innocent citizens unless there are mass public protests.
Fifth, because even if you are in the government (say, a police officer reading this page), you do not want to be part of an increasingly corrupt and repressive system.
Sixth, because youth is being increasingly criminalized by anti-curfew laws, the war on drugs, and measures like Proposition 21. What used to be minor infractions are being made into felonies. Funding for schools is being cut while prison construction grows.
Seventh, because you can be prosecuted for victimless crimes like drug possession or associating with "gang" members while corporate criminals are never arrested for crimes like toxic waste dumping or violating labor laws.
Eighth, to free political prisoners like Mumia Abu-Jamal, Leonard Peltier and Steve Kubby.
Ninth, to avenge Amadou Diallo, Don Scott, and Peter McWilliams, all murdered by the police or the criminal justice system.
Tenth, because the US is globalizing its insane war on drugs/war on crime to protect repressive governments and corporate interests--as in Colombia.
Eleventh, because the United States government is increasingly violating human rights at home and abroad, including using torture and illegal detentions, as documented by Amnesty International.
Twelfth, to get out in the streets and form coalitions with other groups fighting the system.
Thirteenth, because police brutality is not the result of the famous "rogue cops". Police abuse is systemic and frequently encouraged by headline hungry prosecutors and politicians. When you have a government going to "war" against its own people, as it is via the war on drugs, then police brutality becomes the standard.
Fourteenth, because "law and order" are code words for repression--after all, slavery was the law, segregation was the law, censorship was the law, anti-union laws were, well, the law, anti-homosexual statutes were (and still are in some states) the law, etc., ad nauseam.
Fifteenth, because, unfortunately, the police have managed to get themselves on the wrong side of every major struggle for freedom in the history of this country. The police enforced slavery laws, the police enforced segregation laws, the police enforced censorship and anti-birth control laws, the police attacked union organizers, the police today enforce the war on drugs, censor rock music and arrest homosexuals, the police attack rave culture, the police suppress minority religions (Rasta, Branch Davidians)...the list goes on.
Sixteenth, because the police protect corporate elites. It was the police who were lined up in the streets defending corporate elites and their puppets at Seattle, Philadelphia, Washington DC and Los Angeles in 1999-2000. At the same time, the police do not enforce laws against corporate crime. Why the double standard? Because the government is anti-citizen and pro-elite.
Seventeenth, because the government and its corporate partners are using illegal force to attempt to suppress dissent, as they did against demonstrators in Seattle, Washington DC, Philadelphia, and Los Angeles--but we won't let that happen. The more repressive the state gets, the more people will resist. We have the opportunity to expose the system. Let's seize it!