The legal basis of NERC activities
The NERC is operating in accordance with the Law on Energy, the Law on Electricity, the Law on Natural Gas, the Law on Liquefied Natural Gas Terminal, the Law on District Heating Sector, the Law on Energy Resources Market, the Law on Renewable Energy, the Law on Heating Sector, the Law on Drinking Water Supply and Waste Water Management, the Law on Public Administration, Resolutions of the Government of the Republic of Lithuania, the Regulations of the NERC, the Operating rules of the NERC and other legal acts.
All the legal basis can be found in Lithuanian here.