Complex sentence: The most notable act of Crassus and Scaevola's consulship was the "Lex Licinia Mucia", an infamous law that targeted foreigners who were illegally masquerading as Roman citizens.
Split into simpler sentences: The most notable act of Crassus and Scaevola's consulship was the "Lex Licinia Mucia". This was an infamous law that targeted any foreigners who were illegally masquerading as Roman citizens.