With the Internal Electricity Markets - IEM - Directive (2009/72/EC), the EU liberalised the electricity markets of its Member States, and created the framework for a common market for electricity. It requires Member States to introduce labeling schemes for electricity sold to final consumers, providing them with details of the contribution of each energy source to the overall fuel mix of the supplier, and the respective environmental impact. This requires a procedure for allocating electricity generation "attributes", such as fuel type, CO2 emissions etc. to electricity suppliers and their customers.

The RES ( 2009/28/EC) and Energy Efficiency (2012/27/EC) Directives create a framework for the promotion of electricity produced from renewable energy sources (RES electricity), and of cogeneration based on useful heat demand. These Directives contain regulations on Guarantees of Origin, which serve to enable producers of RES electricity and high efficiency cogeneration to demonstrate that the electricity they sell is produced from renewable energy sources or high efficiency cogeneration. Such guarantees of origin provide an efficient and simple means of facilitating disclosure.

Certificates can also be used to disclose other forms of electricity, including that which originates from nuclear and fossil fuels. The existence of certificates for all sources of electricity allows more detailed audits to be conducted of supplied energy, enabling the consumer to be offered products using the fuels sources - and perhaps comprising the cleaner forms of fossil fuel, or zero/low-carbon fuels and technologies. This is in place in some countries (Austria, Sweden, Switzerland), under national law.