In 2009, she was selected as a member of the team in her university participating in the ELSA Moot Court Competition. The team competed both in the Regional Round (Helsinki), being the Runner-up, and the Final World Round which took place in Santo Domingo.
Mariona became interested in international law during her high school studies while participating in a UN Moot Program (MEXMUN) with her school. The ELSA Moot Court Competition served to further focus her interest in international economic law and, in particular, the WTO.
During her law degree she also gained experience in the private sector working for several law firms, one of them the London branch of one of the largest law firms in Spain.
Mariona is native speaking catalan and Spanish, and is fluent both in English and French. She also studied German during her high school.