The NDC's interests are represented by the Executive Board, which essentially governs Noveria and keeps the tech companies there in line. The Executive Board appoints an administrator to oversee day-to-day business on Noveria; when Commander Shepard arrives, the current administrator is a salarian named Anoleis. The administrator's position allows him a great deal of power, which often opens him up to the temptations of corporate corruption. The NDC's Executive Board accepts this and normally tolerates self-interest as long as it doesn't interfere with their business.
Although Noveria is not technically under Citadel law, the NDC allows Spectres special privileges, but they are in a unique position to hamper a Spectre's investigation if it might cause problems for the NDC's investors. Though they will not directly interfere, they can bury the Spectre under litigation and paperwork.
When the NDC discovered Administrator Anoleis was earning kickbacks from lab rents and driving away customers, they appointed an Internal Affairs agent, Gianna Parasini, to gather evidence. Parasini saw Shepard's arrival as an opportunity to get the files she needed to prove Anoleis' guilt, and asked for Shepard's assistance.
Depending on how Shepard chooses to resolve the corruption plot surrounding Anoleis, after Anoleis is arrested, the NDC may appoint Lorik Qui'in as administrator.