Before moving her practice to the Hudson Valley, Ms. Yamashita worked for one of the largest law firms in the world representing clients throughout the New York metropolitan area. She is a former professor of both business law and health law. As a litigator, Ms. Yamashita has represented parties in court appearances, bench trials, administrative proceedings, and jury trials in courts though out New York, Massachusetts, New Mexico, and the District of Columbia. 

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Since 2013, Ms. Yamashita has represented the People of the State of New York in more than fifteen thousand cases in her capacity as a special prosecutor. She handles numerous trials and hearings every month and participates in dispute resolution and other conferences weekly. She litigates matters in the justice courts of eight different jurisdictions as well as the Appellate Division and the Supreme Court.

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Ms. Yamashita served as an officer of the Women's Bar Association of the State of New York (WBASNY), the largest women's bar association in the United States from 2024 to 2025. She served as the president of the Mid-Hudson Women's Bar Association twice, from 2013-2014 and again from 2023-2024. She serves as the vice president of the MHWBA and she serves on the nominations committee of WBASNY. 

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In 2022, Ms. Yamashita founded Nationwide Seminars LLC, a member of the National Safety Council. She is the Chief Executive Officer and a certified Alive at 25 instructor. Thousands of students have taken her courses.

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Ms. Yamashita enjoys running with her daughter and her family has resided in beautiful Rhinebeck, New York since 2007.