The two rhetorical techniques demonstrated in the passage are:
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Hyperbole - The phrase "should be abandoned to a 20th-century paper shredder" exaggerates the idea of discarding the Constitution to emphasize the speaker's strong feelings about its inadequacy in dealing with the offenses charged.
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Juxtaposition - The comparison of the "18th-century Constitution" to the "20th-century paper shredder" contrasts two different time periods and suggests a conflict between outdated and modern values or practices.
So the correct answers are hyperbole and juxtaposition.