The basis for arrest in many cases is often a field test of suspicious substances. A case out of Tampa Florida shows how unreliable these tests can be. A woman was accused for stealing from a Wal-mart store and police tested a vial of something yellow found in her purse. The test showed it was methamphetamine and she was held on drug charges since August 15th. It turns out that it was, as she had insisted all along, dehydrated cat urine for her son’s science project that she had been purchased at an animal clinic.