This Article examines the historical origins of the horizontal effect problem in the United States and Japan. In the United States, from the founding era to the nineteenth century, jurists considered common law rights and constitutional rights had the same scope. Lawyers in the nineteenth century considered that the Due Process Clauses protected common law rights, which originally developed in private litigations. For example, private parties as well as the government shall not infringe on liberty of contract. However, this circumstance changed after the constitutional revolution in 1937. The concept of constitutional rights, distinct from common law rights, has gradually developed since then. The problem of horizontality appears because of the historical fact that constitutional rights and common law rights diverged at that time. In 1946, the framers and lawyers in Japan had the idea that the Constitution applied to private spheres. They expected the government to enforce the Constitution in all legal areas, including private relations. This is because just after World War II, Japan experienced various liberal and progressive social reforms. However, Japanese politics ultimately became conservative. The conservative Liberal Democratic Party had constantly ruled the government. Japanese liberal scholars could no longer expect the government to impose liberal ideologies upon society and they needed an intellectual weapon to combat the government. Japanese lawyers have rebuilt a constitutional theory that constitutional rights are a bulwark of individual liberties against the government, and that the rights only apply to governmental actions. From the time that constitutional theory emerged on, Japanese jurists have had to tackle the horizontality problem.

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美国和日本横向效应问题的历史根源：宪法权利触及私人领域如何成为问题

本文探讨了美国和日本横向效应问题的历史根源。在美国，从建国时期到十九世纪，法学家都认为普通法权利和宪法权利具有相同的范围。十九世纪的律师认为，正当程序条款保护了最初在私人诉讼中发展起来的普通法权利。例如，私人当事人和政府不得侵犯契约自由。但这种情况在1937年宪政革命后发生了变化。与普通法权利不同的宪法权利概念从此逐渐发展起来。横向性问题的出现是由于当时宪法权利与普通法权利存在分歧的历史事实。1946年，日本的制宪者和律师认为宪法适用于私人领域。他们期望政府在所有法律领域（包括私人关系）执行宪法。这是因为二战后不久，日本经历了各种自由和进步的社会改革。然而，日本政治最终变得保守。保守的自民党一直执政。日本自由派学者不能再指望政府将自由主义意识形态强加于社会，他们需要一种智力武器来对抗政府。日本律师重建了一种宪法理论，即宪法权利是个人自由对抗政府的堡垒，并且这些权利仅适用于政府行为。