He said such work should be "an ongoing priority rather than the subject of a one-off operation by the agency".

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He said his view was that "this was a one-off operation, not likely to be repeated" but that "only substantial custodial sentences can meet the requirements of the case".

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There are also guidelines requiring one-handed operation and a two second limit on "off-road glances" - the time spent looking at the device.

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