Responsa for Ketubot 165:11

Q. A had lived undisturbed for more than three years in T when the community ordered him to leave the place because he had received no permission from it to establish a residence there. A claims that the settlement ban against new settlers had been waived for his benefit by all the members of the community who lived in T at the time. The latter deny A's claim.
A. The removal of the ban against settlement by waiver is accepted by the communities as legally binding, although, in talmudic law, rights in real property cannot be waived or relinquished unless the waiver be accompanied by a formal act of possession. But since the community denies A's claim, A must produce proof that the ban against settlement had been waived in his favor. A community is in complete possession of its rights and does not have to protest any encroachments on such rights. Therefore one can not claim usucapion as a factor in obtaining possession of community rights. This law is accepted throughout this Kingdom.
SOURCES: Pr. 46; L. 351; Mordecai Hagadol, p. 308a.

Q. Within the first year of her marriage to A, L claimed that she detested him and could not live with him. Before their marriage, money had been given to L by her father, as a present, on condition that A never have a right to it. L, therefore, demanded this money and the accrued income thereof. On the other hand, L's father had promised a dowry to A but had postponed the date of delivery of such dowry, having expressed the fear that L might rebel against her husband within the first year of her marriage. A, therefore, demands the dowry from L's father.
A. Although no present can be given to a married woman on condition that her husband have no right thereto, such a present may be given to her during the period of betrothal and thereupon the husband will have no right to such present or the income thereof. Therefore, the present and the accrued income must be returned to L. This decision is effective only if L's dislike of A is deep and genuine and is not induced by anyone. The community must pronounce the ban (herem) against anyone holding information relative to this matter; and if it be discovered that someone has induced L to rebel against A, then the money may be withheld from her as a punishment until she repents. The court always has a right to punish one even unduly, if such punishment will help to check lawlessness and indecency. In this case the punishment of L will serve as a warning to other women. Moreover, should A desire to marry another woman, I believe that he should be permitted to throw a bill of divorcement to L even against her will, since she is the rebellious party. A, however, is not entitled to the dowry promised to him by L's father, since the latter had expressed his intention of giving such dowry only in the event that L and A lived happily together.
SOURCES: Am II, 48.

Q. A wants to buy a house. He is afraid to do so, however, lest his wife later legally restrain him from reselling it [since a wife's ketubah constitutes a lien on the husband's immovables]. Should A stipulate that he buys the house on condition that his wife be unable to restrain him from selling it, and if she formally agrees thereto, would such an agreement be binding on the wife; or would it be null and void since she would thus have agreed to a thing that as yet had no existence?
A. The above agreement would be binding on A's wife, for a person may relinquish his claim to rights and privileges before they are created.
SOURCES: Cr. 263; Mord. Ket. 212; Hag. Maim. Ishut 23, 2. Cf. Moses Minz, Responsa 39.