How was Colorado able to legalize medical marijuana if pot is illegal on a federal law?

One of the ideas of our federal system was that states would be given some freedom to try out different kinds of things. A state could serve as a 'laboratory'. For instance, if one state didn't want to have a state income tax but instead a state sales tax, they were free to try that, and if it worked other states might try it. The federal govt. was supposed to pass more important laws, like regulating interstate commerce, foreign policy, immigration policy, etc.

We've kind of lost touch with this idea over the years. For instance in the 70s the fed. govt. decided to pass a national speed limit. They couldn't constitutionally force states to have speed limits, so what they did was to threaten to cut off federal highway aid to states that didn't pass the 55 mph speed limit. Almost everyone thought that was wrong, including people who WANTED the 55 mph speed limit (all six of them!)

When it comes to marijuana, Pres. Obama sees that a growing majority of Americans believe pot should be legalized. So he made a deal. If states want to legalize pot for medical or 'recreational' use, he won't do anything to stop them. He won't enforce federal pot laws at a low level--hassling 'casual' users or state-legal dispensaries. This is called 'prosecutorial restraint' and it's been used many times by presidents. This will allow states to legalize it, then we can watch them for 5 years or so and see how that works out. IOW these states will serve as 'laboratories'.

If Wash. an Colo. and Alaska see huge rises in high school dropout rates, unwed pregnancies, harder drug addiction, traffic accidents from people driving buzzed, or whatever, then we'll know it was a bad idea. If not, then more states will legalize pot and the federal government will finally legalize it nationwide and let individual states ban it if they want!

The next president, of either party, could reverse this decision in a heartbeat. He/she could decide to begin prosecuting again.

It's more complex than just federal law "trumps" state law.

The country was set up with the federal government handling certain things that needed to be at a national level, like defense (the military), and protections for intellectual property, like copyright. Everything that didn't need to be at the federal level was for the states to handle. The U.S. didn't even have a national currency until 1863. (Which brings up the Civil War, and how much states were resisting the federal government telling them what to do, thus trying to secede.)

Things have evolved over time, particularly as regards the federal Constitution and how it's interpreted, and as regards the state/federal balance. The federal level needs to be especially careful stepping on the toes of the states, and it needs to be careful ignoring the will of the voters.

Many laws remain at the state level, like contract law, criminal law, property law, tort law, etc. Sometimes the Supreme Court will interpret the Constitution in a manner that impacts the states. For example, the Miranda warnings for when people are interrogated after arrest came from a 1966 Supreme Court decision. But that was just a federal minimum, guaranteed by the Constitution. The states commonly provide additional related protections above and beyond what the Supreme Court said the minimum standard was guaranteed by the Constitution. And most criminal law remains at the state level.

The Constitution has what's known as the Commerce Clause in Article I, Section 8, Clause 3. It's VERY important. Its interpretation has changed a lot over time, and determines how much the federal government can regulate things that impact interstate commerce. As a simple example, railroads carry goods across state lines. That's going to mean the federal level can regulate related matters. If these same goods stay only in the state, it's usually harder for the government to say it needs to step in. In addition to the Commerce Clause, Congress has a lot of leeway in using its taxing and spending power, and it can influence what the states do via that power as well. As a classic example, it can provide funding for roads (or not) depending on if states implement related things that Congress wants, like speed limits.

For pot, it can impact things nationally, and commonly cross state lines. The federal level will regulate it. But when individual states and voters legalize it, it's hard for the federal level to go to battle, especially if it stays entirely within the state. Also, in addition to the law itself is the question of how many resources are devoted to any given enforcement. When it comes to pot, the federal level can decide its enforcement resources are better spent elsewhere, at least for now.

Your other examples are a bit off. Prostitution is not federally "illegal." Some specific things like importing people for prostitution can be -- but notice, that's "interstate commerce." Again, it's largely up to states if it's criminal in their state, and under what conditions. Gay marriage was not federally illegal. It was up to states. The 1996 Defense of Marriage Act (DOMA) was ruled unconstitutional, and tried to define marriage as one man and one woman for *federal* purposes. While in effect, it did not "trump" states -- it may have messed things up a bit because of the need for federal and interstate interactions, but it did not make same sex marriage illegal in states that recognized it. The Supreme Court just now said the right to single sex marriage is guaranteed by its interpretation of the Constitution. That's a new Constitutional minimum, to which all states (and the federal government) need to adhere, somewhat like how the Miranda rights, or Roe v Wade, went in. There's still a lot that states can do (or not) on top of it.

Anyway, you probably need to read up on the legal system, and what the boundaries are. In particular read up on Constitutional law, especially the Commerce Clause, and the Dormant Commerce Clause. The Constitution (and its interpretations) control the federal/state balance. Interpretations related to privacy, such as for family matters like abortion and marriage, have also continued to evolve, but come from other areas of the Constitution. They're especially tricky, because they come from "implied" rights like privacy that aren't explicitly guaranteed in the federal Constitution. You might want to start with this book:

Colorado was able to legalize medical marijuana within the state boundaries because Obama's Dept. of Justice decided that they would not enforce federal marijuana laws in any state that voted to legalize such usage.
In other words, federal law against marijuana use exists; it just is not being enforced at the state level.
The Obama Administration ceded authority to individual states in these areas.
A different administration can just as easily reassert that authority at a later time.

The Federal government has chosen NOT to enforce marijuana laws in states that 'legalize' it at the state level. It can be argued that the Federal law is unconstitutional anyway, but that is a separate issue.

wow.
Prostitution has NEVER been regulated/ outlawed on a Federal level. Nor was gay marriage illegal federally. You have it backwards.. states DID NOT allow gay marriage, despite no federal law against it. The ruling yesterday was a CLARIFICATION of rights based on the 14th amendment, which in essence said gay marriage falls under that Constitutional right.
Pot still is federally illegal... they just have not pushed to enforce it fully

Marijuana was only legalized at a federal level for the purpose of coercion by the government in the first place. In the second place marijuana is a medicine which should not be abused like any other medicine (the legalization of marijuana as a "recreational drug" is just as much of a crime as the legalization of alcohol as a "recreational drug"). There are able to do this because of the fact that the government of the United States is purportedly allowing individual states to govern themselves, although in reality there are many groups (corporations) who use their money to control the outcome of these types of laws. In america, it's really not about how much you know it's about who you know. So, the same principal applies in politics, because these corporations dominate the market, they dominate elections, because think about it who are the only people who go to vote? these corporations and their associates. Everyone else is too afraid of the government to even be involved in it, and believe me when i tell you these people know this and they know it well. This is how they maintain their dominance and monopolies over the american market.