The Perplexity Trap: How EPO Patent Law Makes Human Writing Look Like AI

A new research paper on arXiv (2607.13044) highlights a growing tension at the European Patent Office (EPO): the agency's 2026 guidelines hold applicants strictly responsible for any LLM-assisted content in patent filings under Article 83 and Rule 42, yet two practical constraints make reliable AI detection nearly impossible.

First, realistic patent prosecution settings typically only have access to consumer GPUs with about 8 GB of VRAM—not the datacenter-class hardware needed for sophisticated AI scoring. Second, Article 84 of the European Patent Convention requires patent claims to be clear and concise, which pushes human drafters toward the same low-perplexity language patterns that AI models naturally produce. This creates a "perplexity trap": human writing can now be statistically indistinguishable from AI-generated text under the very conditions the EPO expects examiners to use.

The paper, titled "The Perplexity Trap: When Patent Law Makes Human Writing Look Like AI," underscores that the EPO's record 2025 filing numbers and the new 2026 guidelines create pressure to triage suspected AI-generated patent text, but the tools and rules may not be up to the task.

If you're involved in patent filings, a concrete step you can take today is to familiarize yourself with the EPO's 2026 Guidelines, particularly the sections on AI-assisted content and the implications of Article 83 and Rule 42. Understanding these rules will help you navigate the complexities of patent filings in an AI-driven world.