The rules of evidentiary admissibility that apply to oral evidence given in open court are equally applicable to evidence given by affidavit. Affidavits must be carefully prepared, the court will not grant a party leave to accept non-compliant affidavits containing mistakes or clearly inadmissible evidence which could have been avoided or ought not to have been included to begin with.
In particular the evidence must:
- Be relevant;
- Not contain inadmissible hearsay;
- Not make statements of belief where the source of the belief is not stated.
- Be confined to such facts as the witness is able of his or own knowledge to prove.
- Not contain inadmissible opinions.
- Not mislead the court.
If an improper affidavit is filed it may be liable to be struck out, whether wholly or in part. In addition, the solicitor who prepared the offending affidavit may find themselves personally liable to an adverse cost order.
 Deputy Commissioner of Taxation v Ahern (No. 2) (1988) 2 Qd R 158 at  and .
 Re JL Young Manufacturing Co Ltd  2 Ch 753 a .
 s92 EA; Wilson v R (1970) 44 ALJR 221; Hollingham v Head (1858) 140 ER 1135.
 Walton v The Queen (1989) 166 CLR 283; Myers v Director of Public Prosecutions  AC 1001; Re Gardiner (1967) 13 FLR 345.
 Re JL Young Manufacturing Co Ltd  2 Ch 753 at .
 r430(1) UPCR.
 Allstate Life Insurance Co & Ors v Australia & New Zealand Banking Group Ltd & Ors (No 32.)  FCA 25.