臺灣當今國家的法律對社會上習慣的規範態度，來自東亞從明治日本於進行法律現代化時，在制定法上即以歐陸式法律規範為主，故社會上的習慣除極少數被納入民法典之外，在國家法上僅能以習慣法以及事實上習慣等兩種身分存在。前揭規範態度及內涵後來傳入清末與民國中國，戰後再從中國回傳至原屬日本殖民地的臺灣。習慣雖較難符合現代法所要求的明確性與可預測性，但在社會上仍可能指引人們的行為，故國家法應適度的接納習慣。臺灣法學界之所以不關心習慣在國家法上的地位，相當程度是因不知這項議題在臺灣一百餘年來發展歷程，亦未深刻省思外來的國家及實證法與在地的社會及習慣之間應有的對話。臺灣在日治前期，國家法就臺灣人的民商事項及臺灣土地關係適用臺灣人習慣法，而非日本現代民商法典，但該等習慣法係以歐陸法概念來詮釋臺 灣漢人社會中的習慣，並以現代的法理念或財產法制為一定的修正。惟無論如何，其展現出一種讓習慣與現代法兩者相容的規範模式。另一方面，日本政權在整個日治時期都不以現代法制統治高山族原住民族，故沒必要將原住民族的習慣詮釋為國家法上習慣法，然理蕃警察因不受限於現代法制通常僅就民事事項容認習慣，反而得以就高山族原住民包括民事、刑事、程序法等事項，均可參酌原住民族習慣而為個案裁斷。日治後期立基於日本國族主義的內地延長政策當道，故為實現「習慣立法」而擬訂的 1914 年臺灣民法草案未被採行，日本的現代民商法典大舉施行於臺灣，臺灣人習慣法可適用的事項已退至僅涉及臺灣人的親屬繼承事項及祭祀公業。日治後期的法院在認定臺灣人身分事項習慣法時，已相當程度否定了某些源自漢人法律傳統的親屬繼承習慣，但所引進的現代法理念仍較 1914 年臺灣民法草案為少，日本民法親屬繼承兩編則因與漢人繼承傳統嚴重衝突而未施行。當時的第一代臺灣法律人對習慣的國家法化雖曾表示意見，但無法形成共識進而主導立法。戰後來臺的國民黨政權，基於中國國族主義而立即且全面的施行中華民國法制，包括原為中國所制定的現代民法典，並無特別關照臺灣在地社會之習慣的立法。是以在民法上被認為係習慣法者僅祭祀公業派下權一例，被視為事實上習慣而當作是當事人法律行為或意思表示的一部份也只有幾例，但亦有如童養媳係以其他法律關係加以包裝後承認之。尤有甚者，司法實踐上從未見原住民族習慣被視為習慣法或事實上習慣。1990 年代民主化以後的臺灣，來自在地社會的國會議員樂於將習慣規範納入法典∕制定法之內，可謂習慣立法的再興；有民意基礎的立法機關更勇於排斥某些不合時宜的漢人法律傳統，但如祭祀公業派下權仍不敢全然顛覆傳統。且國家法終於「看見」了最弱勢的原住民族習慣，例如關於原住民姓名之排除民法之適用，或在刑罰法規上顧及其習慣而為例外性規定。於今原住民族有機會跳脫東亞從明治日本以來、以現代法為單一價值來建構國族國家單一的法體系的模式，而擁有奠基於自己法律文化觀的法規範。且上述立足於臺灣法律社會史所發現的經驗事實，可運用至對臺灣現行法制的法制定（立法論）或法適用（司法論）上。

The attitude of Taiwan’s state law toward societal customs came from Meiji Japan, the first country who tried to modernize its legal system in East Asia. In Meiji Japan, because the statute basically adopted Continental European law, societal customs were not parts of the state law unless they were recognized as “customary law” or “factual customs” in the positive law, although few of customs had been incorporated into the Japanese Civil Code. Such an attitude toward customs was received by China during the late Qing and Republican era, and then came Taiwan, a former Japanese colony, after the end of the World War II. It is difficult for customs to meet the needs of clarity and predictability required by the modern law, but customs indeed influence human behaviors in a society. Partly because of lacking knowledge about legal development of Taiwan in the past hundred year, Taiwanese legal scholars pay little attention to what kind of role custom has played in the state law of Taiwan. During the former period of Japanese administration, Taiwanese civil matters and land relationship in Taiwan were determined by customary law, rather than Japanese modern-style Civil Code. Those old customs of Han Chinese in Taiwan were thus interpreted by legal terminology of Continental European law and selected to be rules in the customary law mentioned above. This kind of combination of customs and modern law in Taiwan was different from that in Meiji Japan or in Republican China. On the other hand, it was not required to rule mountain indigenous peoples by law during the Japanese period, and therefore their customs were not necessarily interpreted as rules in the customary law. The policemen who were in charge of dealing with legal affairs of m ountain indigenous peoples actually took customs into considerations when they made judgment on the cases involving with mountain indigenous peoples. During the latter period of Japanese administration, due to Japanese nationalism, the policy of “extension of homeland” prevailed in colonial Taiwan; not surprisingly, those drafts specifically designed for civil law in Taiwan were never approved by the authorities in metropolitan Japan. Since 1923, the customary law was applicable merely for Taiwanese family and succession matters and ancestor worship. In fact, the colonial court frequently revised Taiwanese customary law, but brought only a few modern elements to Taiwanese law. The succession system in the Japanese modern-style Civil Code was far different from that of Han Chinese so that this code was not suitable for the Taiwanese. The first generation Taiwanese legal professionals discussed the role of customs in the state law from the viewpoint of the Taiwanese; however, they did not reach the consensus and could not promote legislation in a colonial parliament. In post-war Taiwan, the KMT regime ignored the uniqueness of Taiwan on the basis of Chinese nationalism, and did not allow customary law to be governing law in civil and commercial matters in Taiwan. The societal custom relating to the membership of ancestor worship was the only one which was recognized as “customary law” in the state law. A few customs were regarded as “factual customs” and therefore became parts of agreement of parties. By contrast, the customs of indigenous peoples were never recognized as “customary law” or “factual customs” in the post-war state law. Nevertheless, since the democratization of Taiwan in the 1990s, those legislators who are elected by people in Taiwan have been happy to codify local customs so that the customary legislation has re-emerged in Taiwan again after its failure in the 1910s. The current legislature in Taiwan is more confident in overthrowing Han Chinese legal traditions which have become out of date, although it does not completely invalidate the custom relating to the membership of ancestor worship. More importantly, the state law has changed its attitude toward the customs of indigenous peoples. There has been a special legislation to allow indigenous peoples to name themselves by their own customs, and indigenous people could be exempted from criminal sanction on the ground of their customs. East Asian countries have always tried to establish a nation-state with a single legal system for a single value, modernity. It is a possible for Taiwan, however, to shape a state law with legal pluralism now.