Why don't athletes who test positive for steroids get arrested?
 

Or people who fail drug tests for employers?

I don't intend for this to be an argument about whether or not steroids (or drugs in general) should be legalized. But if you're caught under the influence of illegal drugs, you can be arrested. Why isn't it the same for people caught with drugs in their system, since the person presumably had to use the drug to get it inside them?

are steroids illegal? I thought they were used in medicine.

http://www.usdoj.gov/ndic/pubs5/5448/index.htm

They are in fact illegal if you do not have a prescription.

The reason that people are not arrested for testing positive, however, is because no test is 100% accurate. Other chemicals, foods, etc can trigger a false-positive result. I believe that lemon poppy seed muffings (yum yum) can return a false-positive test result for morphine / codeine.

I think that is it: a test that may be good enough for a sports league to issue penalties within the sport isn't necessarily good enough to stand up in a criminal courtroom.

Yes and unless you use in public or are driving under the influence. Most cases it would be a minor misdemeanor (public intox).

Since it is a private company testing and there is no proof of when the drug was used trying to prosecute would be a waste of money, time and truly clog up the courts even more.

No, the difference is consumption versus possession. Most jurisdictions don't have a law against having cocaine IN you, rather on your possession. You can walk up to a police officer high off your ass, but they can't specifically arrest you on the consumption.

Keep in mind that the athlete generally has a team doctor who is prescribing the steroid. So it's legal for him to take it, it's just against the rules of the athletic organization.

I've heard that some sports testing organisations will pass their findings on to police, but I can't find proof of this.

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