Users of commercial legal information retrieval (IR) systems often want argument retrieval (AR): retrieving not merely sentences with highlighted terms, but arguments and argument-related information. Using a corpus of argument-annotated legal cases, we conducted a baseline study of current legal IR systems in responding to standard queries. We identify ways in which they cannot meet the need for AR and illustrate how additional argument-relevant information could address some of those inadequacies. We conclude by indicating our approach to developing an AR system to retrieve arguments from legal decisions.