We all know the police generally must get a warrant before they can search someone's home and seize property. This means going before a judge and demonstrating “probable cause” that criminal activity is taking place at the location.
But judges have wide discretion in granting search warrants, and the criminal activity in question can be practically anything.
Not so with wiretaps. California wiretapping laws (Penal Code 631) make it illegal for private parties to wiretap phones. And they strictly limit the conditions under which even police can employ wiretaps as a law enforcement tool.
Basically court orders for wiretaps can only be granted to investigate the most serious crimes, such as murder or kidnapping. Even then orders are only granted after other, less intrusive investigative means have failed. And strict time limits govern how long a wiretap order can remain in effect.
Penal Code 631 also makes it a crime for private parties to engage in wiretapping. A conviction can land a person in California state prison for up to 3 years.