State Justice Improvement Act This bill reauthorizes through FY2027 the State Justice Institute, a nonprofit corporation established by federal law, and authorizes the institute to award grants for the development and implementation of best policies and practices for the constitutional and equitable enforcement of fines and fees. Specifically, the institute may award these grants to state and local courts, nonprofit organizations, institutions of higher education, and other specified entities. The policies and practices must incorporate guidance that courts should, among other things, consider alternatives to incarceration for defendants who are unable to pay fines.