Ketubot, Chapter Eleven, Mishnah Five
This mishnah deals with a case where a court erred in the evaluation of property while selling it to pay for the widows ketubah or for her maintenance.
1) If an assessment of the judges was one sixth less, or one sixth more [than the actual value of the property] their sale is void.
a) Rabban Shimon ben Gamaliel says: their sale is valid for, otherwise, of what advantage is the power of a court?
2) But if they made a bill for inspection, their sale is valid even if they sold for two hundred zuz what was worth one maneh or for one maneh what was worth two hundred zuz.
Section one: If the assessment was either one sixth less or one sixth more than the real value of the property, the sale sanctioned by the court is nullified. This is similar to the rule of fraud which we learned in Bava Metzia 4:3.
In contrast, Rabban Shimon ben Gamaliel rules that there is no rule of fraud when a court sells. Unlike individuals who sell, their sale may be invalidated if they over or under priced the object by more than one sixth. This idea of Rabban Shimon ben Gamaliel is an idea that he brings up in several places. Basically, the respect for the court is a more important value than the fact that the court actually sold the field for the wrong price.
Section two: If the court made out what is called a bill for inspection then even if they over or under sold by more than one sixth, the sale is valid, even according to the opinion in section one. A bill of inspection is a document that announces that a court will be selling a certain piece of land to pay off a debt. This will allow others to come and inspect the land and if the land is still under or over sold, the court at least has gone through the proper process.