Knotty is an adjective used to describe something with many knots. It can also be used figuratively to express something difficult, intricate or complex.
For several months, the future of those sleek Jaguar saloons and robust all-terrain Land Rovers, symbols of a once-great British motor industry, seemed to hang in the balance as Tata, parent of Jaguar Land Rover (JLR), and government officials wrangled over the knotty issue of financial support. (The Economist)
Analysts see a chance of getting a franchise-focused bill passed into law this year. That’s unlikely, though, if legislation is broadened to include such knotty topics as indecency and wireless spectrum allocations. (Business Week)