You can read the Complaint here. The new rules are most commonly (in my experience anyway) referred to as "quickie election" rules. The plaintiffs have ratcheted up the rhetoric a little bit, labeling them "ambush" elections.
You can read the full complaint for yourself, but here's a recap of the claims:
- Count I - The Final Rule Is Not in Accordance With the NLRA, Exceeds the Board’s Statutory Authority, and Violates the First and Fifth Amendments of the Constitution of the United States; and
- Count II - The Board's Actions Are Arbitrary and Capricious.
The plaintiffs asked the District Court of D.C. to vacate the final rule and enjoin enforcement of the rule.