Criminal law is quite complex, to say the least. There are state and federal laws that govern how law enforcement can act. Then, there are court rulings that apply to these laws. This is especially true when it comes to searches and seizures of private property. There are many procedures that must be followed for the search to be considered legal and constitutional. When the police use dogs to search for drugs, the same is true. The legality of the search depends on many different factors, from federal and state law to the Constitution.