https://www.federalrulesofcivilprocedure.org/frcp/title-v-disclosures-and-discovery/rule-37-failure-to-make-disclosures-or-to-cooperate-in-discovery-sanctions/

Federal Rules of Civil Procedure

Rule 37

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(c) Failure to Disclose, to Supplement an Earlier Response, or to Admit.

(1) Failure to Disclose or Supplement. If a party fails to provide information or identify a witness as required by Rule 26(a) or (e), the party is not allowed to use that information or witness to supply evidence on a motion, at a hearing, or at a trial, unless the failure was substantially justified or is harmless. In addition to or instead of this sanction, the court, on motion and after giving an opportunity to be heard:

(A) may order payment of the reasonable expenses, including attorney’s fees, caused by the failure;

(B) may inform the jury of the party’s failure; and

(C) may impose other appropriate sanctions, including any of the orders listed in Rule 37(b)(2)(A)(i)—(vi).

(2) Failure to Admit. If a party fails to admit what is requested under Rule 36 and if the requesting party later proves a document to be genuine or the matter true, the requesting party may move that the party who failed to admit pay the reasonable expenses, including attorney’s fees, incurred in making that proof. The court must so order unless:

(A) the request was held objectionable under Rule 36(a);

(B) the admission sought was of no substantial importance;

(C) the party failing to admit had a reasonable ground to believe that it might prevail on the matter; or

(D) there was other good reason for the failure to admit.