Among the many disasters that Prohibition wrought (and continues to bring in the form of the current Drug War) it seems it is largely responsible for wiretapping. This again from Last Call:

When he was Attorney General (wintercow: Lord Jeff alum) Harlan Fiske Stone had declared that Justice Department personnel (including members of J. Edgar Hoover’s brand-new Bureau of Investigation) were forbidden to use wiretaps, which he considered unethical.

…

and Chief Justice Taft led a 5-4 majority that found private telephone communication between two individuals no different from casual conversation overheard in a public place. “Can it be said that the Constitution affords no protection against such invasions of individual security? asked Brandeis. For the first time, the Court said it did not.