This research report examines the analysis of the power of the high court to invalidate the law enacted by the parliament in Tanzania mainland, taking Mbeya as the case study. The Topic by this is about the effectiveness of the power of high court to declare the law enacted by the. parliament to be unconstitutional. In addressing this problem, the study under this research raised different hypotheses such as the power of the high court to invalidate the law enacted by the parliament in Tanzania mainland are not effective. In follows consequently that in addressing the said problem the paper goes follows, the research addresses the general introduction in which different methodological issues such as background of the problem, statement of the problem, Hypothesis, Significant of the study, objective of the study, Literature review, research methodology. This research further addresses the conceptual framework of the power of the High court to invalidate the law enacted by the parliament in Tanzania mainland, and mining of different terms and conceptualize on different concept relating to the problem of this research. And also the Research provides legal frame of the power of the high court to invalidate the law enacted by the parliament in Tanzania mainland, it provide different laws which govern the power of the high court to invalidate the law enacted by the parliament in international level, regional level and Tanzania mainland position. Moreover, it provides for the research findings and data analysis on the power of the high court to invalidate the law enacted by the parliament in Tanzania mainland, findings in this chapter are solely basing on the research question which the research provides for the conclusion and recommendation in which inter alia the statement of the problem and thesis statement have been revised. Conclusively this research after strong observation recommend on the Bill which govern the power of the high court to invalidate the law enacted by the parliament and recommends on reform of some provision in the bill before come into force so that it can well protect an ensure the administration of justice in the court of law.