In our current set of laws, rules from the Self-Governing Communities and the European Union are constantly increasing, although state rules haven’t decreased on the same basis. State lawmaking has not been adapted to the new circumstances. Individuals can see how the set of laws has become larger and more complex.

In such context, legislators must obviously take interest in an improved lawmaking technique, so that individuals’ situation doesn’t get worse. Nevertheless, diligence is not being noticed. Our set of laws is very large and its technique is not appropriate.

Interest in lawmaking technique and clarity of rules is especially important in Tax Law. So has our Constitutional Court stated – e.g., in STC 150/90. However, efforts have been focused on administration improvements and the use of telematics systems, rather than on legislation. Taxpayers may profit from the simplification that technological advances bring with, but they don’t realize that, as tax liability is worked out more automatically, their knowledge of rules – which can’t be always found or understood – decreases.

Lawmakers have shown some signs of awareness of the problems about legal certainty – suppression of “accompaniment laws” being the best example –, but they are neither much nor sufficient. Thus, the participation of the legal doctrine is necessary in order to advert the existing technical irregularities and suggest solutions to them. This is the essential aim of this Project.

Key words: Lawmaking technique, Legal certainty, Legislative Power, Tax Law, UE Law, Self-Governing Communities.