With e-cigarettes and flavored vapes booming in popularity, the U.S. Supreme Court on Monday will examine whether the Food and Drug Administration unlawfully blocked the marketing and sale of more than a million new sweet and candy-flavored nicotine products in recent years.

The FDA has rejected applications for more than 1 million fruit, candy and dessert-flavored e-cigarettes and vaping liquids in recent years.

The Supreme Court on Monday pressed the Food and Drug Administration on whether it followed the law in its effort to keep flavored e-cigarettes off shelves, weighing a lawsuit from a multibillion-dollar industry that has come under scrutiny because its products are popular with school-aged children.