What form of legal monopolies still exist today?

Answer 1

Perhaps a better question might be "why do monopolies arise" however the current question will do just fine. And better yet, why can they arise in a democratic nation. Here is a summary that answers the monopoly question:

A. A monopoly is a company that is the sole seller of a product without close substitutes. A monopoly is able to remain as such in a market only if there are barriers to entry of that market. Basically we have a situation where other companies cannot compete with the monopoly company. There are several reasons for these barriers in an open market society:

A1. A key resource of a product is owned by one company. This is rare but as an example, De Beers owns 80% of the diamond mines in South Africa and thus controls the diamond market.

A2. The government has given the monopoly company the sole exclusive right

to produce & sell a product. This is common but the monopoly has a 20 year time limit because the US Patent Office has awarded the company a patent. The long term benefit of patent laws is to enhance creativity and intellectual achievement.

A3. A natural monopoly arises when a single company can supply a good such as water at a lessor price than two or more other companies can. ( here we have a government overseer dept. to safeguard a runaway market ).