Logical ReasoningDifficulty: Hard

PT103 S2 Q23 Explanation

In a certain municipality, a judge

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsPrinciple-Strengthen

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Stimulus

In a certain municipality, a judge overturned a suspect’s conviction for possession of an illegal weapon. The suspect had fled upon seeing police and subsequently discarded the illegal weapon after the police gave chase. The judge reasoned as follows: the only cause for the police giving chase was the suspect’s flight; by an illegal chase is inadmissible; therefore, the evidence in this case was inadmissible.

What this question is testing

Principle-Strengthen

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
23.

Which one of the following principles, if valid, most helps to justify the judge’s decision that the

Answer choices

  1. Opposite4% picked this

    Flight from the police could create a reasonable suspicion of a criminal act as long as other

    This argument wants to believe that there was not reasonable suspicion (in fact, it establishes as much), so this answer is pushing in the wrong direction.

  2. Unrelated to Goal4% picked this

    People can legally flee from the police only when those people are not involved in a criminal

    We need to establish that it was illegal for the police to chase, but this is a rule about whether it was legal for the suspect to run. Those are two different things. Also, this is not even a rule that allows to establish that the suspect was legally fleeing. It only has the power to prove someone wasn't legally fleeing. Legally flee ? not involved in crime at the time

  3. Correct64% picked this

    Police can legally give chase to a person only when the person’s actions have created a reasonable suspicion

    Why this is right

    "only when", just like only and only if, is a Necessary (right side) indicator, so this rule looks like this: police legally ? person's actions created a giving chase reasonable suspicion And of course, the contrapositive is what we need (the test just writes it this way to disguise its relevance): person's actions have not created a ? illegal to give chase reasonable suspicion Since the police were chasing simply because the suspect fled, and a suspect's flight is not an action that creates a reasonable suspicion of a criminal act, this answer establishes that it was illegal for the police to give chase. From there, we know that any evidence collected is inadmissible, so we've successfully proven that this evidence is inadmissible.

    Skill tested: Principle-Strengthen · how this choice captures the argument's function is the move to repeat next time.

  4. Nothing New25% picked this

    Flight from the police should not itself be considered a

    We already knew from the background facts that flight from the police shouldn't be considered a criminal act, because we knew that it doesn't create a reasonable suspicion of a criminal act. If fleeing were itself a criminal act, then of course it would create a reasonable suspicion of a criminal act. It would be a criminal act. So this answer is an inference we could have already drawn from one of the premises. It isn't doing anything to help us with our goal of establishing that this was an illegal chase.

  5. Negated Logic3% picked this

    In all cases in which a person’s actions have created a reasonable suspicion of a criminal act, police can legally

    This is just performing an illegal negation (flipping the lightswitch) on the conditional we want. We were looking for this: if there was no reasonable ? illegal to chase suspicion of criminal act This answer is giving us the opposite of that: was reasonable suspicion ? legal to chase On Sufficient Assumption and Principle-Strengthen, we expect that the correct answer will often disguise our missing link by presenting it in contrapositive form (as the correct answer here did), while a trap answer or two might talk about the right ideas but put them in backwards or opposite order.

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