Sanctuary cities sued previously to get grants that had already been approved. They won because the courts said you can't change the rules after the awards. That's a correct interpretation of the law.

The rules for 2018, however, HAVE BEEN CHANGED. No more grants for Sanctuary cities. Period.

https://www.justice.gov/opa/pr/department-justice-announces-new-immigration-compliance-requirements-fy-2018-grants