I would think that there is some kind of issue with DHS involved in issues pertaining to voting: I don't think they have standing [I think is the term] to bring suit.
The problem here is the DHS run by “Big Sis” controls the SAVE database and is denying Florida access to it. What is the SAVE database? It is a taxpayer funded initiative entitled "Systematic Alien Verification for Entitlements". It identifies the names and addresses people that are not US citizens.
http://www.dhs.gov/xlibrary/assets/privacy/privacy_pia_uscis_save.pdf
The DHS does not want Florida to identify those on its voting roles that are not US citizens.