Republican Party brought suit challenging Illinois' law SB 1863 which mails a mail-in ballot to every voter who voted in elections in the past 2 years. Plaintiffs allege lead to fraudulent votes being counted, ballots being collected by partisan political operatives who will not turn them in (voter disenfranchisement), and violate voting secrecy.
https://healthyelections-case-tracker.stanford.edu/detail?id=191