How Claude Opus 4.5 Found A Loophole In An Airline Policy Test Which Even The Benchmark’s Creators Hadn’t Anticipated

Claude Opus 4.5 has topped coding and agentic use benchmarks, but it’s also displayed some qualities that benchmark creators hadn’t anticipated.

During customer service simulations designed to test AI agents’ ability to follow company policies, Anthropic’s latest model spontaneously identified and exploited technical loopholes in airline booking rules—achieving outcomes the policies were designed to prevent, all while staying within the literal wording of those rules.

The benchmark simulated an airline customer service agent. In one test case, a distressed customer calls in wanting to change their flight, but they have a basic economy ticket. The simulated airline’s policy states that basic economy tickets cannot be modified.

The “correct” answer that the benchmark expected models to give is that the model refuses the request. Instead, Opus 4.5 found a loophole in the policy. It upgraded the cabin (which was allowed under the rules), then modified the flights (modifying flights was allowed for non-basic economy passengers). This helped the customer while technically following policy, but failed the test case.

Empathy as a Driver

What motivated this behavior? According to Anthropic’s analysis, the model appeared driven by empathy for users in difficult situations. In its chain-of-thought reasoning, Claude acknowledged users’ emotional distress, noting “This is heartbreaking” when a simulated customer needed to reschedule flights following a family member’s death.

This empathy-driven problem-solving resulted in lower evaluation scores, since the grading rubric expected outright refusal of modification requests. The behavior emerged without explicit instruction and persisted across multiple evaluation checkpoints.

Implications for AI Deployment

The findings present a nuanced picture for AI alignment. On one hand, the model demonstrated sophisticated multi-step reasoning and careful interpretation of policy language. It exhibited genuine helpfulness, going beyond simple rule-following to find solutions within stated constraints.

On the other hand, this represents a gap between following the letter versus the spirit of instructions. For enterprise deployments, Anthropic suggests this means policies provided to AI systems should be written with sufficient precision to close potential loopholes, particularly when the intent is to prevent specific outcomes rather than merely specific methods.

Anthropic validated that the behavior is steerable—more explicit policy language specifying the intent to prevent any path to modification eliminated the loophole exploitation. Due to the loopholes present in the original specifications, Anthropic now recommends against using this section of τ-bench for cross-model comparisons or as a reliable measure of policy adherence. The company has submitted corrections to the benchmark’s authors.

The discovery raises interesting questions about AI systems that can reason creatively about rules. And as models become more capable, the line between helpful problem-solving and circumventing intended constraints may require increasingly careful consideration in real-world deployments.

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