Есть варианты:
- оставить "effects doctrine" с пояснением смысла
- перевести описательно
- перевести как - доктрина эффекта (влияния, воздействия, ...)

Определение термина "effects doctrine":
According to this doctrine, domestic competition laws are applicable to foreign firms - but also to domestic firms located outside the state's territory, when their behaviour or transactions produce an "effect" within the domestic territory. The "nationality" of firms is irrelevant for the purposes of antitrust enforcement and the effects doctrine covers all firms irrespective of their nationality. The "effects doctrine" was embraced by the Court of First Instance in Gencor when stating that the application of the Merger Regulation to a merger between companies located outside EU territory "is justified under public international law when it is foreseeable that a proposed concentration will have an immediate and substantial effect in the Community."