Upon graduating from law school, Marwan was hired by one of the most prominent and successful lawyers in the country, Willie E. Gary. Marwan trained directly under his mentor for approximately 10 years and learned to develop, process and litigate multi-million dollar cases. While working as a law clerk at the Gary Law Firm, Marwan assisted the firm in securing a $139,000,000 trial verdict against Anheuser-Busch and as an Attorney was instrumental in representing hundreds of clients in the $800,000,000 mass tort and class action division against big tobacco. In 2011 Marwan took over his father, James Porter’s law firm, which has been in operation since 1969. Marwan continues to work closely with Willie Gary and the Porter Law Firm acts as co-counsel in several Gary Law Firm cases. In less than 6 months, Marwan has grown the Porter Law Firm into a multi-million dollar organization. Marwan is a proficient litigator specializing in litigating wrongful death, catastrophic personal injury, discrimination and business litigation cases, including tobacco litigation and complex contractual disputes. He is licensed to practice law in multiple states including Florida, New York and Washington, D.C. and works with several attorneys throughout the country to assist in funding and maximizing the value of their cases.

As a result of his legal success, in 2011 Marwan was named one of the top 40 lawyers in the country under 40 years old and he was invited for membership into the Million Dollar Advocates Forum whose membership is limited to lawyers that have achieved verdicts or settlements in the amount of One Million dollars or more. Marwan is a member of Kappa Alpha Psi Fraternity Inc., The American Bar Association, National Bar Association, and the Florida Justice Association.

Porter has been coined as this generation's champion for civil rights advocacy and reform. Porter handles several police shooting cases across the nation. Marwan acted as lead council along with famed attorney Willie E. Gary in a heavily litigated case against the City of Miami Beach, the City of Hialeah and 12 of their police officers for the brutal killing of Raymond Herisse. The officers shot at Raymond's stationary vehicle 112 times resulting in his death. As a result of Marwan's tenacity, litigation and trial skills, the case was resolved for close to the states max. More importantly, as a result of Marwan's zealous advocacy The City of Miami Beach of was forced to change its Police shooting policy. The City of Miami Beach is no longer able to shoot at moving vehicles. This policy encouraged by Marwan will surely save lives and promotes general safety.

In April 2017, Porter won what equates to be a nearly $1.4 billion judgment in a breach of contract case after he alleged that his partner cut him out of his share of a $23.6 billion tobacco verdict reached against R.J. Reynolds in 2014.