^^^^^^^ CB: As to the 4th Amendment, it only limits actions of the government, state action, not private action. There might be some other privacy statute that would limit Google. But I doubt it because, Google doesn't have anything that isn't sent to them. When you send it to them you give up any right to privacy.
To repeat, it's not "illegal" ,in the sense of a crime, for the government to collect information without a warrant and probable cause to believe a crime has been committed. It just means evidence collected in violation of the 4th Amendment cannot be used in a criminal trial.
^^^^ CB: Part of what I said here is not true. There is a criminal statute against illegal wiretaps. andie 's friend corrected me on this.
Unfortunately, there is also a statute from the post-911/ Patriot Act period , FISA , that makes a special exception to the wiretap for big spooks. So, what I said about no crime at all is wrong; but in the sense that the current wiretaps in the news may not be a crime may be accurate.