How do ISPs respond to lawful requests for subscriber logs and how long does it take?
Executive summary
ISPs generally comply with lawful requests—subpoenas, court orders and search warrants—but the legal route required and the practical response time vary widely: many cable operators keep IP-to-subscriber logs only 90–180 days (some shorter), while some carriers have reported retaining assignment records up to 18 months, which constrains what can be produced [1] [2]. The production timeline depends on whether law enforcement brings an urgent warrant or a civil plaintiff serves a subpoena, whether a preservation hold is in place, and each ISP’s internal processes and legal review [1] [3].
1. How ISPs are legally compelled to respond: paperwork and legal standards
To obtain subscriber-identifying information tied to an IP address, requesters typically must present a subpoena, a court order under the Cable Communications Policy Act, or a warrant supported by probable cause; cable operators in particular expect an order authorizing disclosure before releasing subscriber data in many contexts [1] [4]. Federal statutes such as the Electronic Communications Privacy Act frame the cooperation obligation, and case law shows courts will order ISPs to disclose names, addresses, service dates and payment sources when appropriate [4] [5].
2. What ISPs produce: the usual contents of subscriber-log responses
When compelled, ISPs commonly provide account-level data—account holder name, billing address, service dates, phone numbers and records linking a given IP address to an account at a particular time—though granular traffic content (websites visited, payloads) is generally not supplied because ISPs don’t always retain or are unwilling to disclose full traffic logs [6] [5] [3]. In copyright enforcement patterns, plaintiffs first obtain an IP from a third party and then subpoena ISPs for the subscriber behind that dynamic assignment [6].
3. How long ISPs keep the logs that make disclosure possible
Retention policies are not uniform and are often opaque: many cable operators retain IP assignment (DHCP/lease) records for up to 180 days or sometimes only 90 days, while some large carriers have told researchers they keep such records for 18 months—retention can therefore range from weeks to a year and a half depending on the provider [1] [2]. Because there is no comprehensive federal data‑retention mandate for IP-assignment logs in the U.S., these company-level policies determine whether requested historical mapping is available [2].
4. Typical timelines for responding once a lawful request arrives
If authorities present an immediate warrant, ISPs with internal law‑enforcement portals can often produce responsive account records within hours or days, but civil subpoenas and motions to authorize disclosure commonly take weeks to months because of court scheduling, legal review, and subscriber-notification periods that many providers implement [1] [3]. Preservation requests can buy time when logs are short-lived—practitioners advise sending preservation demands early because moving for court authorization later can run into retention windows [1].
5. Caveats, incentives and where opacity matters
Providers are secretive about exact retention and internal turnaround procedures, partly to avoid gaming by bad actors and partly because of commercial/legal sensitivities; this secrecy creates friction for both investigators and defendants and incentivizes preservation holds and faster court processes in time‑sensitive cases [2] [3]. Alternative viewpoints emphasize that ISPs don’t typically log content and that privacy laws like state consumer-privacy regimes or CPNI protections can limit disclosure, while plaintiffs—especially in mass copyright suits—are known to rely heavily on expedited subpoenas to extract subscriber identities before records age out [4] [7] [6].