With cannabis cultivation up 15% in the last year alone (and if that's only going on the amount of cannabis known about by police ? given the incredible smarts of most cannabis dealers, it can only be the tip of the iceberg), thoughts are turning to what to do about it. One of the tactics settled upon has been to encourage people to grass up their local grass growers. Logical, you say, everyone loves a snitch. But how to make the request? Phone and you'll get an earful; knock on the door and you'll be ignored. The answer, as hit upon by cop-associated charity Crimestoppers, is more sophisticated: deploy scratch and sniff technology.

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