Testing, tracking and tracing ingredients is expensive but not testing will cost retailers, processors, British farmers and consumers much more.

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What if the systems were not involved at all, but someone made a mistake in the complicated forensic analysis that accompanies tracking and tracing?

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He said federal laws don't require the tracking and tracing of medicines, though companies are developing a plan, and California has a law that starts taking effect for manufacturers in 2015 .

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Sidney Jones, of the International Crisis Group, says the police are getting much better at tracking down suspects and tracing their accomplices.

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