Answer:
a) In order to search and seizure the officer has to obtain a warrant from a judge. They must have probable cause, supported by oath and affirmation. They must also describe the location that is to be searched or what things are to be seized.
b) Law-enforcement officials can conduct a search without following the requirements of the Fourth Amendment when the illegal substances are in plain view of the officer. As a result of the case Horton v. California, law enforcement does not need a warrant to gather evidence that is in plain view. Also, according to the results of Terry v. Ohio, law enforcement can carry out a stop and frisk if they suspect the accused has illegal substances on their person.
c) In the case Mapp v. Ohio the Supreme Court ruled that all evidence gathered illegally could not be used to convict a person of a crime. Following this court case, Terry v. Ohio decided that law enforcement have the right to carry out a stop and frisk. Then, Horton v. California decided that law enforcement does not need a warrant for illegal substances that are in plain view. The Supreme Courts interpretation evolved by realizing what is required and how the Fourth Amendment rights are limited.
Hope this helps!!
- Kay :)