Both statutory (national state laws) and customary laws (local, traditional, non-state social systems) are followed in Burma, sometimes simultaneously in the same place. Overall, it can be generalized that in the uplands of ethnic areas customary land practices prevail, and the lowlands follow statutory laws. However, there are of course many exceptions; for one the ethnic uplands have been terrorized by war and conflict for generations, which has led to fleeing, internally displaced persons, militarization and compromised traditional practices all of which have weakened traditional social systems and their land management practices.
The situation now is that customary land practices appear to be on the wane. In ceasefire areas the state is extending their control over land and populations, with their attendant land categories (e.g., forest and agriculture rather than agro-forestry systems). And in active war zones local ethnic populations are kept from practicing their traditional swidden cultivation due to the constant threat of warfare and fear.
Upland ethnic populations now find themselves stuck in the crossfire of the rough transition to an opening market capitalism where land is transferred from smallholder farmers to large private companies, both Burmese and foreign. As previously customary laws were honored and the state had not reached the uplands in most ethnic states, most households in the rural uplands do not have any land registration titles. During the British colonial times a few formalized customary rules were enacted and in some small ways recognized for certain areas of the uplands of northern and western Burma. For example, the Kachin Hills Manual (specifically Chapters 3 and 7) respected customary authority of Kachin headmen, and for the Chin specific laws were created to address their customs, called the Chin Hills Regulation 1896, and the Chin Special Division (Extension of Laws) Act, 1948.
The SPDC does not legally honor customary rights and laws, with inadequate provisions in the new constitution to uphold customary traditions. In practice, however, there is a messy informal overlap between customary and statutory laws and practices, where SLRD officers record customary agricultural land plots for their surveys and maps, but at the same time is not honored when desired by an influential developer backed by the state. It is this grey area with respect to the customary-statutory spectrum that causes land tenure insecurity for millions of farmers in Burma, especially in the ethnic uplands.
Land tenure remains very weak in Burma, especially in the uplands where customary practices are still often followed instead of statutory law. A fundamental problem is that no law formally recognizes traditional upland land use. This means that if a farmer wants to practice customary shifting cultivation, then that practice will not be formally recognized by the government, and thus there is no way to legally protect this traditional land management practice. The Community Forestry Instructions, while a good opportunity, are often not implemented as a traditional land management strategy and thus change the way local people use, access and manage land. They are jointly managed with the Forestry Department and often promote growing timber rather than food.
References: The Burma Environmental Working Group (BEWG) report, "Burma's Environment: People, Problems, Policies"