Complex sentence: It was in existence from 1955 until the Treaty on the Final Settlement in 1990, but was only constituted once in 1979 to hear the jury trial of the LOT Flight 165 hijacking defendants.
Split into simpler sentences: It was in existence from 1955 until the Treaty on the Final Settlement in 1990. The Court was only constituted once in 1979, to hear the jury trial of the LOT Flight 165 hijacking defendants.