When an Arkansas court rules whether the prosecution can use the illicit drugs found on your person as evidence for possession charges, it must determine if the search and seizure was legal.
According to FindLaw, the two main factors involved are your constitutional right to the expectation of privacy and probable cause for police to conduct the search.
Expectation of privacy
Briefly stated, the Fourth Amendment guarantees your right to security and privacy. This means that if law enforcement officers found the drugs by invading your privacy, the search was illegal. The law bases your expectation of privacy on your belief and the general acceptance that the location was actually private.
For example, you probably consider everything in your briefcase or house as your private belongings, and society, as a whole, agrees with you. Therefore, a search of those locations by public authorities is unreasonable and illegal unless they have probable cause to believe they might find evidence to support a specific charge. Conversely, you generally cannot go back and claim a privacy violation for something ambiguous, like an open picnic basket in the park.
Probable cause
The theory of probable cause allows police to use common sense investigation to search and seize evidence. Law enforcement officers frequently use this theory to get around the expectation of privacy. For instance, if they pull you over for speeding and either see drug paraphernalia in plain view or smell marijuana smoke, they have probable cause to search your car, even though they were not initially looking for drugs.
However, the lack of probable cause can exclude found evidence of possession and lead to the dropping of your charges. Using the same speeding example, if the authorities decide to search your car because they did not like the loud music playing, any illegal substances they find are likely inadmissible.