The lawsuit in Cook County Circuit Court argues that the state Board of Elections shouldn't spend public funds on two proposals to amend the Illinois constitution that it calls invalid.
The first would establish term limits for lawmakers and is led by GOP gubernatorial candidate Bruce Rauner. The second would create an independent commission to draw legislative district lines.
The plaintiffs say the measures are not valid because they do not meet a constitutional requirement for changes to the Legislature.
The plaintiffs' attorney is Michael Kasper, who is general counsel for the Democratic Party of Illinois. The party chairman is Democratic House Speaker Michael Madigan.