The End Goal and Jury Nullification

Here's the Wikipedia article:

Jury nullification occurs in a trial when a jury reaches a verdict contrary to the weight of the evidence and contrary to the letter of the law (an official rule, and especially a legislative enactment). A jury exercising its power of nullification need not disagree with the judge's instructions themselves—which concern what the law is—but may rule contrary to the instruction in light of the actual evidence admitted in the case.

Here's a practical application of the idea from the writers of The Wire:

If asked to serve on a jury deliberating a violation of state or federal drug laws, we will vote to acquit, regardless of the evidence presented. Save for a prosecution in which acts of violence or intended violence are alleged, we will — to borrow Justice Harry Blackmun's manifesto against the death penalty — no longer tinker with the machinery of the drug war. No longer can we collaborate with a government that uses nonviolent drug offenses to fill prisons with its poorest, most damaged and most desperate citizens.

Although I know where I stand on illegal drugs, I'm not completely sure where I stand on taking the court system into my own hands. It's like trying to reach a goal, which in this case the goal is to treat citizens fairly, by ignoring the rules originally set in place to reach that goal. Here's the Economonomics blog ("putting the econo back in economics"):

You've probably heard this one before: The principal has some complicated objective he wants the agent to pursue, but he can't get the agent to care about this objective directly. Instead, he can only create a bunch of rules that approximately incentivize the right behavior [...] 

The thing is that objectives are rarely simple, but rules generally need to be. Simple to communicate, simple to follow, simple to measure whether people are violating the rules or not. Therefore rules are biased towards being simple, whether the objective that generated them is complicated or not.

So do are we more likely to have a fairer society if juries ignore what they perceive to be unjust laws. I just don't know.