Why is India's probe of Scotch imports from Britain rattling liquor majors?

India's investigation into bulk Scotch whisky imports has triggered the first major trade dispute under the India-UK free trade agreement. The government argues bulk Scotch does not qualify for reduced import tariffs, potentially restoring duties to 150% from 75%. The dispute threatens a $65 billion global whisky market, putting Diageo, Pernod Ricard and Indian liquor makers at odds with customs officials.