When Is It OK To Disobey The Law?

In the news recently, Arizona has decided to enforce federal immigration laws at the state level.  While many of their ideas were struck down by the US Supreme Court, some parts of their new law remain in effect.

Arizona basically lost confidence in the US Government enforcing its own laws, so Arizona decided to enforce it for them.  For some reason, the US Government has a problem with that...

You see, if the law is the law, it should be enforced.  If you don't like the laws, change them.  If they're not changed, they must be enforced.

Conversely, the US Government has banned the sale or use of marijuana in all shapes and forms.  Fifteen states (and the District of Columbia), thumbing their nose at the government, decided to pass laws making it legal to use marijuana legally if used for medicinal purposes.

State law tried to overrule Federal law, and the DEA and Dept of Justice cried foul.  (Again, for some reason, the US government has a problem with state laws...)

So, in a nutshell, states cannot enforce federal laws if the federal government doesn't want to, and states cannot pass laws that overrule government law.

...but what about States passing laws that overrule federal laws that the government doesn't want to enforce?

Even though the Defense of Marriage Act was passed in 2006, defining as law that marriage is between one man and one woman, the government doesn't feel like enforcing the law.  States jumped on this, and now gay marriage is legal in six states, with another six having odd rules about recognition and certain timelines.

...

AM I THE ONLY ONE WHO IS COMPLETELY FUCKING CONFUSED BY ALL OF THIS?

On a personal level, I am pro gay marriage, pro marijuana (safer than alcohol), and mixed about immigration.  On a logical level, I am completely baffled why the government (state or federal) can't make up their mind one way or another on these laws.

And now that the Supreme Court has ok'd the Affordable Care Act (aka 'Obamacare'), it will be interesting to see how the battle of 'Federal vs State' plays out in the next few years.  (Speaking of Obamacare, I love all the idiots saying 'if it gets enacted, I'm moving to Canada/Costa Rica/etc.'  Most of their examples already have laws like this in place!)

Both sides of the political fence are crying '10th Amendment' for these various laws in one way or another.  While there have been clauses and exceptions made on behalf of the 10th Amendment, the line between who is really in charge gets blurrier and blurrier.

Can someone explain to me how we let things like this get so out of hand?  I really don't care if you're for or against any of these laws, I just want to make sense of the muck.

Should these types of laws be handled on a federal level or by the states individually?  And why?  I would love to hear your opinions on this.

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