Before that, Jonathan served on the Newburgh City Council, where he championed improving the City's infrastructure. Early in his career, Jonathan served as an Assistant Counsel to the Speaker of the New York State Assembly, where he researched and wrote legislation for the Labor Committee. As an Assistant New York State Attorney General, he headed the Consumer Frauds Bureau at the Poughkeepsie Regional Office. He continued his public service career as a New York State Workers' Compensation Law Judge.

Jonathan had his own private law firm, first concentrating on real estate and business law, and for the last part of his legal career, Jonathan focused on representing workers in Workers' Compensation and Social Security disability cases.

Jonathan is a product of the Newburgh public school system, having graduated from Newburgh Free Academy (NFA). He graduated from Duke University, cum laude, with Honors in Political Science. Jonathan went on to graduate from New York Law School.

Since being elected, Jonathan has focused on fighting gun violence; utility reform including holding Central Hudson accountable for illegal, incompetent and predatory billing practices; workforce development; preventing corruption and conflicts at industrial development agencies; protecting reproductive health rights and making voting simpler and easier.