A more thorough explanation:

The Noerr–Pennington doctrine is a principle that protects companies from legal liability, especially under antitrust laws, when they join together to lobby the government. This principle is based on a series of Supreme Court cases, including Eastern R.R. Presidents Conference v. Noerr Motor Freight, Inc. and United Mine Workers v. Pennington.

For example, if two competing companies in the same industry join together to lobby the government for a change in regulations that would benefit their industry, they would be protected by the Noerr–Pennington doctrine. Even though their actions may have anti-competitive effects, they are shielded from legal liability because they are exercising their First Amendment right to petition the government.

Another example could be a group of farmers lobbying the government for subsidies or tax breaks. Even though these actions may benefit the farmers at the expense of taxpayers, they are protected by the Noerr–Pennington doctrine because they are exercising their right to petition the government.

These examples illustrate how the Noerr–Pennington doctrine protects companies and individuals from legal liability when they engage in lobbying activities. It is important to note that this doctrine only applies to lobbying activities and does not protect companies from liability for other anti-competitive behavior, such as price-fixing or market allocation.