Network analysis of lawyer referral markets: Evidence from Indiana

Using network analysis, we study referrals among plaintiff-side lawyers handling medical malpractice cases in Indiana. The referral network is stratified, with a few highly connected “hub” firms. Firm connectivity follows a power law distribution—suggesting that new entrants tend to associate with already well-connected firms, rather than starting a new network. Regression analysis shows that, for a given firm, connectivity (i.e., node degree) in the referral network and being loyal to a smaller number of firms both lead to better outcomes in non-referred cases. The referral network also became more concentrated over time. The stratification of the market for plaintiff-side representation is reinforced through these processes.