Consider the following facts:

The police arrested a suspect for a drug sale and took his cell phone as a part of the arrest. The police then performed a warrantless search of the cell phone and discovered information which led them to a large drug bust of crack, cocaine, and other drugs. A conviction for distribution of crack cocaine ensued.

Did the police violate the defendant’s Fourth Amendment rights by searching his phone without a warrant? Why or why not? What are the legal issues involved?