Sean T. O'Neill

Sean T. O'Neill
Primary Office

Sean O'Neill handles commercial and real estate litigation matters for energy companies, developers, higher education institutions and insurance companies, among others. He also advises clients on environmental social and governance (ESG) related issues and provides counsel in connection with project development. Sean has an extensive track record of success with seeking and defending preliminary injunctions for his clients and representing clients in administrative appeals relating to real estate and project development.  

Sean focuses on litigating complex legal issues and helping clients develop solutions that align with their goals. His experience representing clients across multiple industries helps him to understand the unique issues and perspectives of clients as they navigate the opportunities and challenges posed by rapidly evolving rules and regulations relating to ESG.  


Sean represents energy companies in litigation relating to infrastructure projects, renewable projects, contract disputes and construction-related damage claims. Sean has extensive real estate litigation experience, with a focus on eminent domain, but also including landlord-tenant disputes, evictions, confessed judgments and quiet title actions. He handles various administrative appeals in connection with real estate development projects, including zoning appeals, tax assessment and exemption appeals, historic designation appeals and outdoor advertising sign appeals. He also represents insurance companies in various complex litigation matters, such as reinsurance coverage disputes, challenges to insurance regulations and claims involving insolvent insurers.