This section is from the book "Popular Law Library Vol7 Equity Jurisprudence, Trusts, Equity Pleading", by Albert H. Putney. Also available from Amazon: Popular Law-Dictionary.
This maxim means that all persons seeking equitable relief must accord to the other parties concerned all the equitable rights in the suoject matter to which they are entitled. Under this principle one who has failed to perform his own obligations under a contract, cannot compel the other to perform.22
"The principal applications of the maxim are in suits to rescind contracts or to avoid other transactions, where plaintiff is required to restore benefits received and place other parties in statu quo,23 election,24 marshalling,25 in bills for relief against usury,26 and before the married women's acts in enforcing the wife's equity to a settlement.27 The adverse equity which must be satisfied is sometimes raised by estoppel."28 29
20 Van Voorhies vs. Van Voorhies,
94 Mich., 761; Woodward vs.
Woodward, 41 N. J. Eq., 224. 21 Sincheimer vs. United Garment
Workers of America, 77 Hun.
(N. Y.), 215. 22 Wood vs. Perry, 1 Barb., 114;
Baltimore vs. Chesapeake, etc.,
Telephone Co., 92 Md., 692; 48 Atl., 465.
23 Stewart vs. Ludwick, 29 Ind.,
24 See Descent and Distribution,
14 Cyc, 1, Wills.
25 See Marshal of Assets and Securities.
26 Corby vs. Bean, 44 Mo., 379.
The application of this maxim is not limited to the complainant; it is available against a cross-defendant,30 and sometimes even against a defendant. The Supreme Court of the United States said on this last point in the case of Brown vs. Lake Superior Iron Co.:31
"The maxim 'He who seeks equity must do equity,' is as appropriate to the conduct of the defendant as to that of the complainant; and it would be strange if a debtor, to destroy equality and accomplish partiality, could ignore its long acquiescence and plead an unsubstantial technicality to overthrow protracted, extensive, and costly proceedings carried on in reliance upon its consent. Surely no such imperfection attends the administration of a court of equity. Good faith and early assertion of rights are as essential on the part of the defendant as of the complainant."