EncroChat ruling has ‘far-reaching effects’ for legal role of interception in UK investigations

by Joseph K. Clark

The key question considered by the Court of Appeal was the distinction between temporary, transient, random-access memory (RAM) and permanent data storage in modern digital communications systems.

In computer science and technology, the distinction between memory and storage is fundamental. Until 2021, RAM and processor registers and memory store areas were understood to be an integral part of every digital transmission system – unlike records such as voicemails left and stored when phone calls do not connect.

There now appears to be no legal distinction between temporary memory and data stores inside computing devices. The Appeal Court explained: “The 2016 Act does not use technical terms … experts have an important role in explaining how a system works, but no role whatever in construing an Act of Parliament.”

EncroChat ruling

The court said that when data in a phone call, video call, or message is temporarily held in RAM as an “essential part” of a transmission system, it is “stored”. This was true even if data was stored only for nanoseconds. “Parliament has not chosen to define the ‘relevant time’ when interception takes place by reference to whether the communication is in the RAM of the device at the point of the extraction,” the court pointed out.

The UK is the only country in the common law world that bans the use of intercept evidence in legal proceedings and has even criminalized inquiries or suggestions about whether interception has been used. According to the all-party criminal law reform group Justice, Britain’s 65-year-old ban is “archaic, unnecessary and counter-productive”.

The UK’s Investigatory Powers Act 2016 requires ISPs and CSPs secretly to install additional software and equipment to carry out authorized “lawful interception” of telecommunications. Except for some new types of “bulk interception”, this is usually done by software inside switches and routers, not by tapping into fibers or intercepting radio transmissions.

The new ruling could enable police and other agencies, when tapping computers or phone calls carried or switched digitally, to decide to bring intercepts into evidence when they choose, merely by obtaining an “equipment interference” warrant to cover the role of the software alterations installed to do lawful interception. The decision fundamentally changed UK policy on intercept evidence, based on the new legal meaning of “memory”.

When we experience “latency” in phone or video calls, meaning that information may be seen or heard or messages received seconds or even many seconds after the event, most of the delay is the time the data spends in numerous RAM stores and registers en route, including during analog-to-digital conversions, buffering, serialization and digital signal processing. Because of this, most data communications spend almost all of their transmission time in temporary storage – so they could now legally be copied using warrants for equipment interference applied at any midway point.

A call going from Birmingham to London (200km along roadside or railside routes) could, in theory, travel at just under the speed of light in air, or at two-thirds of the speed of light in a cable, so would reach a London listener in about a millisecond. If the actual delay is a hundred milliseconds (one-tenth of a second) or more, the data has been in some form of storage and could be copied without “intercepting” during at least 99% of its journey.

The Court of Appeal verdict says that former legal understandings of when communication starts and stops are an “obvious error”. Under previous rulings, the transmission was defined as beginning when a microphone hears a speaker and ending when a recipient hears a loudspeaker sound from their receiver.

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