A Colonial Authority is a corporation that has been delegated key responsibilities of the state within a specific region of space. Colonial Authorities are invariably influential mega-corporations with a significant number of government contracts – so significant that the state has determined that it’s better to keep them happy than it would be to run the risk of pissing them off.
The designation is typically granted to corporations that provide services deemed vital to human health and security, whose assets and income total more than sixty percent of the gross domestic product of the company’s geographical area of operations, and for whom the state (or a major state contractor) is the primary source of revenue.
A rough equivalent would be the East India Company.