Legal Question in Criminal Law in Florida

The answer depends somewhat on the substance, but generally no. The standard for arrest is probable cause, which is not very high. If the officer can swear that the evidence shows it was more likely than not an illegal substance based on his/her training and experience or other evidence then an arrest can be made. The most common case would be for Marijuana and Rx pills (which are usually identified by poison control or the drug bible based on markings). More exotic substances like the bath salts, PCP, or LSD would probably require field testing.