Law of Indonesia is based on a civil law system, intermixed with customary law and the Roman Dutch law. Before the Dutch colonisation in the sixteenth century, indigenous kingdoms ruled the archipelago independently with their own custom laws, known as adat. Foreign influences from India, China and Arabia have not only affected the culture, but also weighed in the customary adat laws. Aceh in Sumatra, for instances, observes their own sharia law, while Toraja ethnic group in Sulawesi are still following their animistic customary law.
Dutch presence and subsequent occupation of Indonesia for 350 years has left a legacy of Dutch colonial law, largely in the Indonesia civil code. Following the independence in 1945, Indonesia began to form its own modern Indonesian law, not developing it from scratch, but modifying precepts of existing laws. Dutch legal decisions maintain some authority in Indonesia through application of the concordance principle. The three components of adat, or customary law; Dutch-Roman law; and modern Indonesian law co-exist in the current law of Indonesia.
Indonesia legislation comes in different forms. The following official hierarchy of Indonesian legislation (from top to bottom) is enumerated in Article 7 of Act No 12 of 2011, a "Law Concerning Making Rules":
In practice, there are also Presidential Decrees (Keputusan Presiden, Keppres), Presidential Instructions (Instruksi Presiden or Inpres) (most famous to build the Inpres elementary schools), Miniterial Regulations (Peraturan Menteri or Permen/PM), Ministerial Decrees (Keputusan Menteri or Kepmen/KM) and Circulation Letters (Surat Edaran), which sometimes conflict with each other.
Once legislative products are promulgated, the State Gazette of the Republic of Indonesia (Lembaran Negara Republik Indonesia) is issued from the State Secretariat. Sometimes Elucidation (Penjelasan) accompanied some legislations in a Supplement of the State Gazette. The Government of Indonesia also produces State Reports (Berita Negara, lit. "State News") to publish government and public notices as well as ministerial regulations and decrees.
The 1945 Constitution is the highest legal authority in Indonesia, to which the executive, legislative and judicial branches of government must defer. The constitution was written in July and August 1945, when Indonesia was emerging from Japanese control at the end of World War II. It was abrogated by the Federal Constitution of 1949 and the Provisional Constitution of 1950, but restored after the President Sukarno's decree on 5 July 1959. During the 32 years of Suharto's administration, the constitution had never been amended. Suharto refused to countenance any changes to the constitution and the People's Consultative Assembly passed a law in 1985 requiring national referendum for the constitution amendments.
After the Suharto's fall in 1998, the People Consultative Assembly amended the constitution four times in 1999, 2000, 2001 and 2002. Important amendments include the direct presidential election by the people (third amendment) and the presidential office term from unlimited to only two (first amendment), the regulation of which had made the possibility for Suharto's administration held in office for more than five terms. After the last amendment, the People's Representative Council gained more power to control the executive branch, the Regional Representatives Council was established, regional government was recognised in a section and an expanded section about civil rights among other changes. Currently, the constitution consists of 16 sections and 36 articles.
Undang-Undang (English: Acts, usually translated into Laws) can only be established by the People's Representative Council (the DPR). The executive branch (the President) can propose a bill (Indonesian: Rancangan Undang-Undang or RUU) for consideration by the DPR. During the process of considering a bill, the DPR usually creates a small task group to discuss the proposed legislation with the relevant government ministries. When agreement has been reached and the DPR has approved the bill, the President usually endorses the bill and it is promulgated as Act. However, even if the President refuses to endorse a bill approved by the DPR, the bill is automatically enacted within thirty days and is promulgated. When agreement cannot be reached reached within the DPR to enact a bill into law, the bill may not be proposed again during the current term of the legislature.
There are still many problems with the legal system in Indonesia. Many laws and regulations conflict with each other, and because the legal system (including the courts) sometimes does not operate effectively, it can be difficult to resolve these conflicts. Further, the rule of law in Indonesia is often undermined by rife corruption among the nation's judiciary and law enforcers.
The overall legal system is badly under resourced, both in the public sector and the private sector which provides many services to clients. For example, in early 2015 it was reported that there was a severe shortage of judges which was particularly affecting the operations of district courts (pengadilan negeri). It was reported that around 250 new judges were needed each year but that no new judges had been appointed for four years. At the time, Indonesia was reported to have a total of around 8,300 judges but that around an additional 1,000 judges were needed to fill the backlog.
The Indonesian government and professional lawyers in Indonesia are well-aware of these problems and are working, over time, to improve the system.