Complex sentence: The case turned on the fact that the 23rd District was a protected majority-Hispanic district--that is, if the 23rd was ever redrawn in a way to put Hispanics in a minority, a new majority-Hispanic district had to be created.
Split into simpler sentences: The case turned on the fact that the 23rd District was a protected majority-Hispanic district. If the 23rd were redrawn to put Hispanics in a minority, a new majority-Hispanic district had to be created.