Gifted Issues Discussion homepage Forums Learning Environments test scores used as screening at charter school

I am part of a study group that is visiting gifted schools. At a relatively new charter school, an administrator indicated that they could not legally discriminate based on test scores. She said that charter schools that do screen for test scores are somehow grandfathered in.
Is anyone familiar with this law? Why does it apply to charter but not traditional public schools? Please educate me.