آخر تحديث - 2 ديسمبر 2020
But reflection is a common law lesson that can be suspended according to the principles of justice. Historically, England had two separate judicial systems, and the Court of Chancery, which exercised its last authority of the king over the Lord`s chancellor, prevailed over the common law courts. This also applies to its just principles since the merger of the systems in 1875.  The doctrine of change of sola estoppel states that if one person gives insurance to another person, the other defers to him and that it would be unfair to retract the assurance that that person will be prevented from doing so: an analog of the maxim that no one should profit from his own wrongs (nemo auditor propriam turpitudinem allegans). For example, Hughes` House of Lords v. Metropolitan Railway Co found that a tenant could not be dismissed by the landlord because he had failed to meet his contractual obligations to repair, that the opening of negotiations on the sale of the property had given tacit assurance that the repair obligations would be suspended. And in Central London Properties Ltd v High Trees House Ltd, Denning J stated that during the Years of World War II, a landlord would be prevented from claiming normal rents because he had ensured that half the rent could be paid until the war. The Court of Appeal went further in a recent debt repayment case, Collier v P-M J Wright (Holdings) Ltd. Arden LJ argued that a partner who had been assured that he should repay only one-third of the company`s debt instead of being jointly responsible for the whole relied on insurance by repaying it. , and it was unfair for the financial company to subsequently request full repayment of the debt.
Therefore, the Estoppel of Solawechsel could circumvent the common law rule of Foakes. However, the Promissory estoppel was found incapable of raising an independent remedy, so that it can only be invoked to deter another party from imposing its strict legal rights as a “shield” but not to withdraw a means as a “sword”.  In Australia, this rule was relaxed in Walton Stores (Interstate) Ltd/Maher, where Mr. Maher was encouraged to believe that he would have a contract to sell his land and began demolishing his existing building before Walton Stores finally told him they did not want to enter into a conclusion. Mr. Maher received generous claims for his loss (i.e. damages, but apparently damages for the loss of expectations, as if there was a contract).  However, where a guarantee concerns property rights, a “propriety estoppel” variant allows an applicant to assert estoppel as a means of redress.