Economists are often called upon as expert witnesses by the parties involved in antitrust litigation. One challenge they may face in US federal courts is compliance with the Daubert standard of admissibility of expert testimony. The interplay between model applicability and the Daubert standard is analyzed, suggesting the importance of distinguishing between weak applicability claims, those that state that a model’s critical assumptions are shared by the target, and strong applicability claims, those that connect empirical models and quantitative market features. (...) Recent antitrust cases in which expert testimonies based on economic models have been assessed following the Daubert standard are examined using this framework. Some normative implications are drawn concerning how to improve judges’ assessment of model-based arguments. (shrink)