I believe that the public are entitled to privacy and that the usual fear mongering rhetoric e.g. pedos, terrorists, organised crime, mutant frogs and so on is no excuse for this additional infringement of public liberty.
Recently the EU has dreamt up a new law that demands that search engines retain users search data for two years to allow the authorities to have a little snoop around, if they feel like it.
You can read further details here:
Britain should oppose this intrusive measure.