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The ABC of EU Law: Key Concepts Every AD5 Candidate Must Know

Essential EU legal concepts from the official reference material. Treaties, legal instruments, competences, and the principles that govern the EU legal order.

"The ABC of EU Law" is one of the 13 official reference documents for the AD5 EU Knowledge test. At nearly 200 pages, it's the most comprehensive — and the most frequently tested. Here are the key concepts you need to know.

The EU Treaties

Two treaties form the constitutional basis of the EU:

Together, these are the "primary law" of the EU. Everything else derives from them.

Types of EU Legal Acts

Article 288 TFEU defines five types of legal instruments:

InstrumentBinding?Key Feature
RegulationYes, fullyDirectly applicable in all member states — no transposition needed
DirectiveYes, as to resultMust be transposed into national law — states choose the method
DecisionYes, on addresseeBinding on those to whom it's addressed (a state, a company)
RecommendationNoSuggests action without legal obligation
OpinionNoExpresses a view on a matter

Exam tip: The most common question type asks you to distinguish between a Regulation and a Directive. Remember: Regulation = directly applicable; Directive = requires transposition.

EU Competences

The EU can only act within the competences conferred by the treaties. Three categories:

Fundamental Principles

Principle of Conferral

The EU has only the competences that member states have conferred upon it in the treaties. Anything not conferred remains with the member states.

Subsidiarity

In areas of shared competence, the EU should only act if the objectives cannot be sufficiently achieved by member states alone. National parliaments can raise objections ("yellow card" procedure).

Proportionality

EU action must not go beyond what is necessary to achieve the objectives of the treaties.

Supremacy of EU Law

EU law takes precedence over conflicting national law. Established by the Court of Justice in Costa v ENEL (1964).

Direct Effect

EU law can create rights that individuals can invoke before national courts. Established in Van Gend en Loos (1963). Regulations have automatic direct effect; directives can have direct effect if clear, unconditional, and the transposition deadline has passed.

Common Exam Traps

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