Complex sentence: She filed several lawsuits on issues over which she felt there was a collusion of church and state in violation of the United States Constitution, including a lawsuit against the city of Baltimore demanding that it assess and collect taxes on property owned by the Catholic Church.
Split into simpler sentences: She filed several lawsuits on issues over which she felt that the United States Constitution was violated by a collusion of church and state. One was against the city of Baltimore demanding that it assess and collect taxes on property owned by the Catholic Church.