(NVR) - Though wineries throughout the U.S. regularly source wine grapes grown in Napa Valley, the right for winemakers to call their finished product “Napa Valley” wine may soon extend only to the California state line.

A proposed rule amending the current federal regulation is poised to limit the use of American Viticultural Area (AVA) names, such as “Napa Valley”, in the labeling of wine produced in a state other than the one containing the AVA from which the grapes are sourced.

Using what some have called a ‘loophole’ in the regulation, wineries countrywide can currently apply for an exemption that allows them to source grapes from out of state vineyards and use the name of the grapes’ AVA, so long as the finished wine is sold only in the state where it is produced.