Ladas was born in Athens in 1891. He studied Law at the University of Athens and,having graduated, became a lawyer at the Court of First Instance in 1912. In 1919, he became a lawyer at the Greek Supreme Court. He defended the leadership of the Greek Communist Party (KKE), accused of high treason, in August 1925 and February 1926.
After World War II, he was again elected to the Hellenic Parliament and became Minister of Justice of the Sofoulis government. As such, he promoted legislation to outlaw the KKE which was then waging a civil war against the national government. For this, Ladas was attacked and blown up with a hand grenade, by communist Efstratios Moutsoyiannis, as he exited the church of Saint George on Holy Saturday, May 1, 1948.
Moutsoyiannis and his eight accomplices were sentenced to death on June 21, 1948. Six of the accused were executed by firing squad on June 25 but Moutsoyiannis and his chief accomplice, Dionysios Kampanidis, had their sentences converted to life imprisonment due to their repentance and co-operation with the police authorities after the crime.
The street on which Ladas was killed now bears his name.