They want to find who committed <some crime they just made up that isn't actually bad>, so they identify DNA and compare it against the known database.
This is pretty standard "how will we respond if there is a future authoritian regime"? (not saying the fear is unjustified - just saying the fear is pretty standard)
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Edit:
People are really misunderstanding my comment. Let me try again.
To be clear, this is hypothetical:
The government makes it illegal to support anyone of opposing political party. Which includes, not buying from their store. They go to the restaurant of the opposing party and run a DNA test on all of the silverware. They arrest anyone whose DNA matches the DNA on the silverware - because those people "supported" the opposing party.
This is pretty standard "how will we respond if there is a future authoritian regime"? (not saying the fear is unjustified - just saying the fear is pretty standard)
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Edit:
People are really misunderstanding my comment. Let me try again.
To be clear, this is hypothetical:
The government makes it illegal to support anyone of opposing political party. Which includes, not buying from their store. They go to the restaurant of the opposing party and run a DNA test on all of the silverware. They arrest anyone whose DNA matches the DNA on the silverware - because those people "supported" the opposing party.