Complex sentence: The public at large is usually more familiar with the International Court of Justice than with the Permanent Court of Arbitration, partly because of the closed nature of cases handled by the PCA and to the low number of cases dealt with between 1946 and 1990.
Split into simpler sentences: The public at large is usually more familiar with the International Court of Justice than with the Permanent Court of Arbitration. The fact that people are relatively unfamiliar with the PCA is due to the closed nature of the cases and to the few number of cases dealt with between 1946 and 1990.