They want you angry, they want you very angry.  It’s emotion that drives the collective; it’s emotion that drives the mob; it’s emotion that drives democracy to totalitarianism.

There’s a reason the founding fathers of the U.S. Republic promised a “republican form of government“, a constitutional republic and not a democracy.
A Republic is ruled by principles of law, and as a consequence it is a representative process of considerable debate and deliberative conversation.
A Democracy is ruled by majority, by emotion.  Debate is not considered – the arguments are short and quick – the rules quickly assembled without lengthy forethought toward consequence.  (If that sounds like ObamaCare, it’s not coincidental)
Not a single Democratic form of governance has ever survived itself and not devolved into fractured revolution.  Because, quite simply, the minority view is always oppressed and never considered.  Eventually, and historically, the disenfranchised minority breaks away, forms a new government, and tries to avoid the same mob mistakes.  Hence, you flee and form the Mayflower Compact.

What we are all bearing witness to is this very simple “constitutional republic” concept being undermined via a backdoor application of pressure toward our constitutional framework.
The death of Eric Garner is a consequence of following such collective governance to its natural conclusion.  To be sure those applying the pressure don’t want you to look out that far – they need you focused at your feet.
The same entities who would arrest a man for selling individual cigarettes, would arrest a man for selling a Big Gulp, or even a restaurant owner for allowing open access to table salt.  Why?  Because they’ve convinced the Democrat majority it’s good for them.
The Democrats created the black market which Eric Garner was engaged in.  Yet, they wouldn’t want you to connect those dots either.
The forces who work to undermine our constitutional republic necessarily need to shift the conversation away from the immediate, and into their framework of the “bigger picture”.
They don’t want you to apply common sense logic to the reality that Trayvon Martin would be alive were it not for his decision not to go home, to choose to be combative, and to punch George Zimmerman in the face.
They don’t want you to apply common sense logic to the reality that Michael Brown would be alive today were it not for his decision to punch a police officer in the face and wrestle for his gun.
They need you to focus on the emotion of a dead 17-year-old, or a dead 18-year-old.  This was abundantly evident today when President Obama, responding to the events around Eric Garner, said clearly:

“It is incumbent on all of us as Americans regardless of race, region, faith, that we recognize that this is an American problem and not just a black problem or a brown problem or a Native American problem. When anybody in this country is not being treated equally under the law, that’s a problem. And it’s my job as president to help solve it.”

Emphasis mine.  Let me clear up the underpinning ideological flaw, and reset the paradigm:

“When anybody in the country is not BEHAVING EQUALLY under the law, that’s a problem”.

See the difference?
Everyone is treated equally under the law, but not everyone behaves equally.  What the Democrat ideologues need to convince you – is that this self-evident truth is non existent.

To achieve this goal, they change perception of the behavior; they change the definitions, and they obfuscate the dynamic at hand.
The construction of changing the acceptable social dynamic flows outward as a consequence of their intents.
Statements like: “He (the victim) was in the wrong place at the wrong time”; “he (the victim) shouldn’t have gotten out of his car”, etc.  All intended to change the traditional social dynamic and allow the unlawful to be considered acceptable.
The victim dynamic flips upside down.  The dead thug is now the victim, the abused is now responsible for his/her beating, shooting, (fill_in_the_blank), for not following some unrecognized mob rule.
Obviously those rules are not covered in legal doctrine, hence when the emotional arguments are dragged into court, they fail.
The acceptable behavior, or lack thereof, is outlined in law (See: it’s not ok for a 25 year old teacher to have sex with a 16-year-old student, regardless of how much they love each other; or, it’s no ok to punch a police officer in the face just because he’s telling you to get on the sidewalk).
The emotional approach runs head-first into the legal reality and collapses.
Those invested in the emotional outline stand aghast at the collapse of their position.  How is this possible, wha…, the…  he/she didn’t deserve..? etc.
Trayvon Martin was an individual example unrelated to any other.  Mike Brown is an individual example, again unrelated to any other.  Similarly Eric Garner is an individual example unrelated to any other.

It is entirely because you understand the difference that you are able to find yourself with outrage for the Garner case, and yet not with Martin or Brown.  The ability to see the difference is also reflective of the observer valuing the individual over the collective mindset.
The collective mindset, driven by emotion, is why progressive ideologues cannot draw distinction between the cases.  The progressive needs to find an alternative reason, the proverbial *other reason*, to reconcile the emotional failure.  Currently racism is the preferred other reason.
Like you, I find the Eric Garner case very troubling; yet I can also see how a combative person violating simple lawful commands is setting themselves on a path of danger.
Should the police have gone full spider monkey (chokehold) on his back to bring him down?  I think not.  Yet they were asking nicely and he denied their requests.
Should they have tazed him?  Perhaps, but that’s hindsight.
How do you arrest a 400lb man who refuses to comply?  That’s an honest question. Why are you arresting a 400lb man for selling cigarettes, is entirely another.
Within the former question you debate the application of law.  Within the latter question you debate the survival of our Republic.