依據行政院公共工程委員會頒布之工程、財務及勞務採購契約範本中皆規定「契約變更及轉讓」條款，機關得於契約所約定之範圍內通知廠商變更契約，但「契約所約定之範圍內」之解釋基礎何在？如變更不在契約所約定之範圍內將如何？競爭廠商可否抗議機關應另行採購而非逕行行使變更契約之權利？機關是否對該廠商為無正當理由之差別待遇？是否不當限制廠商完全及公開競爭？由於本詞語意並不明確，有賴司法及行政案例解釋方可解決上述爭議。然我國對於機關通知廠商變更契約之行為是否將造成廠商間之不公平競爭等規定仍付諸闕如，故應以理論基礎檢視我國及先進國家包括美國及若干歐盟成員國之相關法律及實務，以研究我國法制是否有應修正之處。本文主要依據美國聯邦法規，包括聯邦獲得規定及審計長之判斷予以論述，以尋求解決方法，首先檢視美國及我國於辦理政府採購時，對於廠商間完全及公開競爭之要求，再自法律層面研究上述歐盟國家採購機關妥適之處理方式，以實證美國採購法制之合法性，本文同時檢視我國內國法令及實務，並研究爭議之掌理機關，俾能了解我國法規疏漏之處，最後謹提供立法之建議，以供參考。

The Model Contract Terms and Conditions for Procurement of Constructions, Goods and Services, promulgated by the Public Construction Commission, Executive Yuan, includes 'Changes and Transfer'claus es, which gives the government within the general scope of the contract the unilateral right to order corrections in the contractual process, if necessary, during the course of performance. What is the basis of interpretation of the phrase 'within the general scope of the contract'? What will happen if the change goes beyond the scope of the original contract? Can competitors protest to the government's issuance of corrections in lieu of using new procurement procedures? Can agencies, without proper reasons, discriminate against these competitors? Can agencies improperly confine competitors' full and open competition? Since this phrase is somewhat vague, it must be subject to judicial and administrative interpretation able to resolve these disputes. There are no laws or regulations supervising the government agencies' ordering power of changes in the context of fair competition. It becomes necessary to review the laws and practice of the R.O.C., and refer to those of developed countries including the U.S. and some E.U. members to see whether amendment to the law or regulation of the R.O.C. is required. This research on agencies' ordering power of changes focuses on the clauses of US Code, the Federal Acquisition Regulations (FAR) and some E.U. members' procurement regulations. Some decisions made by the Comptroller General dealing with issues in this area are discussed. What this research first describes is the requirements for the full and open competition and the practice of the R.O.C. laws and those of the U.S. It then accounts for appropriate regulations of agencies' ordering power of changes. We have examined domestic laws, regulations, and practice of several E.U. members regarding the government's procurement to compare to the validity of U.S. laws. This research also points out some flaws of Taiwanese domestic laws and regulations. In brief, the governing agency of the disputes is studied. At the end, we aim to present some suggestions to establish better laws and regulations for the legislature's reference.