Achieving conservation goals in protected areas hinges on continual monitoring, enforcement, and legal defense. In an era of devolved governance, nonprofit land trusts have become increasingly important. Yet, their approaches to legal defense of conserved areas are relatively unknown. A national survey of 205 land trusts provides the first quantitative data on the types, costs, and outcomes of major legal challenges. Half of land trusts reported a legal challenge, and one-quarter of those land trusts were hindered by financial barriers in pursuing a legal challenge. Interviews with land trust staff revealed the necessary conditions for pursuing legal defense including organizational capacity, community support, and persuasive property claims. Results indicate the importance of stewardship endowments and the need for greater land trust capacity and accountability. Donors, agency funders, and the public should support thoughtful, contextually appropriate, and powerful enforcement actions to ensure conservation objectives over the long term.