On the US side of the pond, the police have found an ingenious way to
sidestep all restrictions placed upon them by this meddlesome
Constitution, Congress, and various laws: they (claim that they) do not
retain data themselves, but they let commercial databases and providers
do that for them, and then the police become these commercial outfits'
best customers. ChoicePoint is one such major comemrcial database keeper
and its customer list reads like a "who's who" in law enforcement.

Since the US Constitution only deals with what the government may not do
unto one and not with what a civilian may or may not do unto another
(with the exception of slavery), the letter of the law is upheld when
Congress degrees (as it has) that the police may not collect and retain
information unless some conditions are met. At the same time, the police
have full access to all this information as commercial customers of this
commercial database keeper who is under no legal restriction not to
retain anything.