Haris started his career in the City of London in 1994. Dispute resolution represents a large part of his practice and he has acted in hundreds of arbitrations, High Court, Court of Appeal, Supreme Court and multi-jurisdictional cases ranging from modest demurrage claims to mine off-take and oil and gas disputes worth hundreds of millions. His reported Court cases include the Johnny K, Trafigura v Kookmin Bank, the Sabrewing, the Northgate, the Port Russel, U&M v Konkola Copper Mines, CH Offshore v PDVSA Petroleo and Petrosaudi Oil Services v Novo Banco et al. While he has been described as a "solid and tenacious litigator" (Chambers UK 2007) and “a supreme tactician” (Chambers UK 2020), he is also involved in non-contentious work, structuring transactions, drafting terms and advising clients on decarbonisation strategy.

He is member of the editorial board of Shipping and Transport Law Journal, member of the Institute of maritime law of the University of Southampton and has served on the Council of the London Shipping Law Centre. He is chair of the International Working Group on maritime decarbonisation of Comite Maritime International. He has published and lectured extensively worldwide, including at COP, for BIMCO and the IMO.

Haris heads the firm's commodities practice, which has repeatedly been recognised as a First Tier team by The Legal 500. The same directory described him as "leading a true team, perfectly organised, providing excellent legal and commercial advice". He has also been inducted to the 2018 Legal 500 Hall of fame as a result of his continued recognition by the directory. 

"a first-class litigator with great technical knowledge and strategic nous"

The Legal 500 UK 2013