Field trial finds AI lifts junior patent attorneys' work, but the gains vanish when the tool is removed

A National Bureau of Economic Research working paper reports a three-month randomized controlled trial with 133 patent attorneys at eleven US intellectual property law firms. The study looked at a contested question: whether AI assistance builds professional expertise or erodes it. Two-thirds of participants got access to InFlow, an unreleased AI assistant from Google Labs. The remaining third worked without AI. Google funded the study. Attorneys first worked on patent claim drafting tasks, and the AI group used the assistant. All participants then evaluated results without it. That design let researchers measure both the quality of AI-assisted work and how well the attorneys' own judgment held up afterward. Blinded patent attorneys at an independent firm scored the work on enforceability, technical accuracy, strategic ambiguity, completeness and clarity. AI assistance improved immediate performance, especially for junior attorneys. But when the AI was taken away, only senior attorneys kept the benefits. The finding matters for law firms and other employers that rely on junior staff learning on the job: tools that raise output quickly may not build the skills those employees will later need on their own.