Depending on how one classifies market intervention, trade liberalization disciplines can be lenient or strict. Perhaps the most important distinction in this respect is that between government intervention labeled as a "market access restriction" and that defined as "domestic regulation." Both the GATT and the GATS declare market access restrictions (such as import quotas or limitations on the number of service suppliers) to be, in principle, prohibited. In contrast, domestic regulations (such as internal taxes, health standards, and safety requirements) are treated with much more deference. They are, in essence, only prohibited when discriminatory or more trade restrictive than necessary. Notwithstanding these major legal consequences, the distinction between market access and domestic regulation remains unclear. Based on a recent WTO dispute condemning the United States for banning online gambling, this article is an attempt to clarify the distinction. Starting from broad similarities, it finds crucial differences in this respect between GATT and GATS. For both, however, the paper's basic point is that a domestic regulation should not be regarded as a market access restriction simply because it has the effect of banning certain imports. To do otherwise risks seriously undermining the regulatory autonomy of WTO Members beyond anything imagined by the drafters of the WTO treaty.
Joost H. B. Pauwelyn, Rien Ne Va Plus? Distinguishing Domestic Regulation From Market Access in GATT and GATS, 4 World Trade Review 131-170 (2005)