About Lesley
Lesley Hauser built a legal foundation in two languages. She earned a B.A. in Spanish Language and Literature from the College of the Holy Cross in 1990, followed by an M.S. in the same field from Middlebury College in 1991. She then turned to law, receiving her J.D. from Loyola University New Orleans in 1994.
Her career began in private practice soon after law school. She joined the Law Offices of Joseph F. O Neil, P.C. as a senior associate in 1995. That role gave her day-to-day courtroom and client experience, and it connected her to the firm that would become the centerpiece of her professional life. Over time she took on broader responsibilities and moved into firm leadership.
By 2008 she was serving as president of O Neil Hauser Mansfield, P.C. That title reflects an evolution from associate to firm leader. It also marks a steady presence in the Massachusetts legal community. She is admitted to practice in Massachusetts and has standing before the U.S. District Court and the First Circuit. Her membership in the Massachusetts State Bar dates back to 1994.
Hauser has been active in professional associations for much of her career. She has belonged to the American Immigration Lawyers Association since 2008. She also holds membership in the Massachusetts Bar Association, which she joined in 2005. These affiliations underline a practice that engages both state and federal procedural issues and places her among peers who handle immigration and related matters.
Her experience spans courtroom work and client counseling. Early years as a senior associate involved litigation and case preparation. Later responsibilities as firm president added administrative oversight and strategic decision-making. The trajectory reflects steady professional growth rather than abrupt change. It shows a lawyer who has moved through familiar stages of practice while maintaining ties to the same firm.
She continues to practice at O Neil Hauser Mansfield, P.C., where she handles immigration matters and related federal and state proceedings. Her work remains grounded in the regional courts and the federal benches where she is admitted to practice.
