made a gift subject to an agreement is unable to put himself in seisin; recourse must  be had to a superior. He will be given an action based upon the agreement when he is  out of seisin; when he is in seisin, he will be given an exception based on the agreement.1
Matters which bar restitution by the assise.
 Uncertainty, whether as to the thing itself, the body or2 tenement, or as to a right  appurtenant to the tenement, or as to the person of the plaintiff [impedes restitution].3  I do not say this if certainty may by some means be secured or at least a presumption  raised, but if certainty can in no way be reached nor any presumption  raised.4 Negligence or dissimulation for a time, which are taken for consent, are also  impediments to restitution, not to the extent of destroying the action completely,  but to that of taking from the disseisee the right to re-eject immediately, for dissimulation  and gross negligence, which is taken for consent, gives the disseisor a quasi free  tenement, so that he cannot be ejected without judgment, and takes his privilege  from the disseisee, for since he is negligent it is at least presumed that he was not  unwilling to be disseised,5 and also that he has lost both possessions, natural and  civil. Similarly consent, whether it exists from the beginning or is given subsequently,  remits the injuria and quitclaims the tenement. A transactio [the compromise of a  doubtful claim] also impedes restitution, as where, for the avoidance of strife, he  remits part of the tenement and accepts part, which may be allowed him as a matter  of grace and for the furtherance of peace, not de jure, for with respect to things done  against the peace of the lord king there is no concord or compromise, only judgment,  according as the plaintiff withdraws or the disseisor acknowledges the disseisin. Confirmation  or consent also impedes restitution: [confirmation], as where the disseisee  confirms the things seized to the disseisor, for a confirmation willingly made nullifies  an injuria; consent, as where the disseisor makes a gift and the disseisee consents to  it and ratifies it, when it is first made or after a time.6 The disseisee's usurpation, without  judgment, of his own property after the disseisin also impedes restitution, but  only after time has passed, as where a disseisee is negligent in impetrating or prosecuting  or both; he cannot usurp his own property without judgment, as above.7 He  may accept it, however, if it is freely offered him. [Only sometimes, not always,8 for  example, A. disseises B., C. disseises A., or A. gives the tenement to C.; B. impetrates  against A. A. fearing the disseisin and the assise ejects C. without judgment and  restores the tenement to B., after impetration by C. or before. If C. sues A. alone and  not B., A. cannot restore. If he sues B. alone, B. did not disseise C. He thus must sue