Look at Marijuana use and ultimate incarceration. The data are that whites use Marijuana at a about the same rate as blacks so for every 5 whites, one black uses marijuana. In our current criminal "justice" system this is how more blacks would end up in prison than whites.
Let's start with 1000 whites who use marijuana and 200 blacks and evaluate the reasons more blacks end up in prison than whites.
First arrest rate
Blacks are 3.73 times more likely to be arrested for marijuana possession so assuming an arrest rate of 10% for whites (this works for whatever arrest rate you choose) you have 100 whites arrested and 74 blacks arrested.
Next convictions
Blacks are 1.3 times more likely to be convicted of crimes after arrest than are whites. Assume a 50% conviction rate for whites and you have a 65% conviction rate for blacks.
So 50 whites convicted and 48 blacks convicted.
Next sentencing
Blacks in Cook county Illinois are sentenced to incarceration 51% of the time while whites are convicted 38% of the time. Assuming whites and blacks are sentenced to similar amounts of time (blacks in general receive sentences 67% longer than whites in Florida prisons for identical crimes) that leaves us with 19 whites and 24 blacks in prison even though 5 times as many whites commit the same crime.
Obviously this is just one example of the problem with several stages of the so called "justice" system (and the actual arrest rate and conviction rates are almost certainly off but the ratios and resultant disparities are correct).
There are multiple reasons these things happen in the system that result in injustice and blacks have cause to call into question their disparate treatment primarily by cops, but the small disparities in each stage by prosecutors, juries, and judges can result in very large disparities in imprisonment.
That's reason enough for me not to question anyone's refusal to accept the American flag as a symbol of freedom. Many blacks see the flag on the shoulders and standing behind the backs of people who do not treat them equally before the law and therefore see the flag as a symbol of oppression rather than freedom.
How to fix it? Colin Kaepernik and and I are actually doing the wrong thing in bringing the disparities to the attention of the public. A Stanford study showed that bringing the racial disparities in prison populations (along with the disparities in arrests, convictions, and sentencing) to light actually increases support for harsher penalties that disproportionately effect blacks. Some studies have shown that directly addressing these disparities with police, prosecutors, and judges (but not jurors), has a short term effect on these disparities.
I support decriminalization of drug offenses but that only decreases the raw numbers and has been shown to have no effect or little effect on ratios of arrests, convictions or sentencing.
Remove the incentive to disproportionately arrest, convict, and sentence blacks. A lot of this has to do with incarcerating the easiest marks. Cops, prosecutors and judges are evaluated by how well their arrests, convictions, and judgments/sentencing are upheld. Blacks are easy marks, they're less likely to hire attorneys that appropriately represent them among other reasons.