Gonzales and FBI Director Robert Mueller have discussed the proposal with ISPs who have considered lengthening their current retention periods on a voluntary basis to avoid legislation. ISPs tend to oppose data retention laws because of the increased cost and responsibility it puts on them.
"This is a problem that requires federal legislation," said Gonzales at a hearing of the Senate Banking Committee. "We need information. Information helps us make cases."
The Banking Committee was investigating ways of combating child pornography and has also been looking into how co-operation with credit card companies could help, as well as how ISPs could help law enforcement.
"We have to find a way for internet service providers to retain information for a period of time so we can go back with a legal process to get them," said Gonzales.
Any data retention law would not preserve the content of communications, only logs of email, internet and phone activity. The telecoms companies would keep the data and it could be accessed only by court order in the same way as a physical search.
A letter to Congress recently contained the support of 49 state attorneys general for a law mandating data retention.
Data retention laws have been passed across Europe and earlier this year a EU Data Retention Directive was passed. Civil liberties groups often oppose the move, though, because the information can be used for other purposes, not just for chasing child pornographers, and because it could leak out of the telcos or government agencies.
In Ireland a case has just been launched by TJ McIntyre of Digital Rights Ireland. It believes that the Irish data retention law is unconstitutional and that the EU Directive violates the European Convention on Human Rights.
"If we're successful it will strike down the Data Retention Directive and that will invalidate a lot of the data retention laws across Europe," McIntyre told OUT-LAW. "We're hoping that there will be a knock on effect. A ruling on the human rights case would be very persuasive for national courts."