Mario is a named partner at Johnson & Sullivan, Ltd. in Chicago, Illinois.  He counsels clients on a wide range of issues relating to real estate, landlord/tenant, creditor bankruptcy, employment, contract law, business formation, and estate planning. 

Mario serves as 2014-2017 Nominating Committee Representative for the ABA Young Lawyers Division (YLD); a 2014-2015 YLD Liaison to ABA Judicial Division and American Bar Endowment; a 2014-2015 Council Member on the ABA Council on Racial and Ethnic Diversity in the Educational Pipeline Council; Co-Chair to the ABA Individual Rights & Responsibilities Bullyproof Committee; a Board Member and Co-Chair of the Program Committee for the LAGBAC; and a Board Member to the LGBT Bar. 

Mario is a former PILI Intern and member of the Public Interest Law Initiative (PILI) Alumni NetworkLeadership Council, and has previously served as: 2013-2014 YLD Chair, 2012-13 YLD Chair-Elect, 2011-2012 YLD Secretary-Treasurer, 2010-2011 YLD Conference, Program, and Products Director, 2009-2010 YLD Diversity Director, Committee member to the ABA YLD Diversity Team and Resolutions Team, and National Representative for the LGBT Bar to the YLD; Vice-president of LAGBAC; Planning Committee - Fundraising member for Equality Illinois 2005 Gala; Chair of the local host committee for the LGBT Bar’s Lavender Law – 2007; and Chair and vice-Chair of the CBA Committee on the Legal Rights of Lesbians and Gay Men.