The U.S. Supreme Court seemed to struggle Monday with rules for trademarking generic names that are combined with the .com phrase.

Many justices seemed to agree with an attorney for Booking.com that a 132-year-old Supreme Court precedent probably doesn’t control the case. But they also sounded wary of granting an online monopoly over entire categories of goods and services, and that it could lead to a flood of litigation over similar sounding dot.com names.