SCOTUS today decided Goodyear Tire & Rubber v. Haeger, addressing the requirement for imposing discovery sanctions under inherent power. It is a short, unanimous opinion, but worth reviewing for its overall discussion (in both text and footnotes) of the sanctions options available to district courts.
In particular, see how the various statutory, rule-based, and inherent sources of sanction power relate and run out. Plaintiffs were complaining about discovery abuse (refusal to produce certain documents), but misconduct not discovered until after the case had settled. So what source? Not FRCP 11, since sanctions cannot be sought once the case ends. Not FRCP 37, since the sanctions for non-production all related to an ongoing case and the appropriate sanction--entering a default--is not an option to a settled case. Not § 1927, since that gets at the attorney, not the party (and it appears the misconduct was by the party, not trial counsel). So the court had to fall back to inherent powers.