The Union Public Service Commission (UPSC) is a central recruiting agency in India, established under Article 315 of the Constitution. It is an independent constitutional body responsible for conducting examinations for appointments to All India Services and Central Services, and for advising the President on various service matters. Its primary objective is to ensure a merit-based and impartial selection process for the civil services.

Powers and Functions of the UPSC (Article 320):

1. Recruitment to Services:

   • Conducts examinations for appointments to All-India Services (IAS, IPS, IFS), Central Services (Group A and Group B), and various other Union posts.
   • Conducts interviews for direct recruitment to various posts.
   • Assists states (if requested by two or more states) in framing and operating schemes of joint recruitment for any services for which candidates possessing special qualifications are required.

2. Consultative Functions: The UPSC is consulted on the following matters:

   • Methods of Recruitment: All matters relating to methods of recruitment to civil services and for civil posts.
   • Principles of Appointments: The principles to be followed in making appointments to civil services and posts, and in making promotions and transfers from one service to another, and on the suitability of candidates for such appointments, promotions, or transfers.
   • Disciplinary Matters: All disciplinary matters affecting a person serving under the Government of India in a civil capacity, including memorials or petitions relating to such matters.
   • Claims for Legal Expenses: Any claim by a person who is serving or has served under the Government of India in a civil capacity that any costs incurred by him in defending legal proceedings instituted against him in respect of acts done or purporting to be done in the execution of his duty should be paid out of the Consolidated Fund of India.
   • Claims for Injury Pensions: Any claim for the award of a pension in respect of injuries sustained by a person while serving under the Government of India in a civil capacity, and any question as to the amount of any such award.

3. Advisory Role: The advice tendered by the UPSC is generally advisory and not binding on the government. However, the government usually accepts its recommendations. If the government does not accept the advice, it must lay a memorandum explaining the reasons for non-acceptance before both Houses of Parliament.

4. Annual Report: The UPSC presents an annual report on its performance to the President, who then lays it before Parliament.

How UPSC has Maintained its Impartiality: UPSC's impartiality is crucial for maintaining public trust in the civil services and ensuring that appointments are based on merit rather than patronage. Several constitutional provisions and operational practices contribute to its independence and impartiality:

1. Constitutional Status: UPSC is a constitutional body, not a creation of an executive order. This gives it a high degree of autonomy and protection from political interference.
2. Security of Tenure: The Chairman and members of UPSC are appointed by the President for a fixed term (6 years or until 65 years of age). They can only be removed by the President under specific circumstances (e.g., misbehavior, insolvency, infirmity of mind or body) and only after an inquiry by the Supreme Court, whose advice is binding on the President. This protects them from arbitrary removal.
3. Conditions of Service: Their conditions of service cannot be varied to their disadvantage after their appointment, ensuring financial security and preventing executive pressure.
4. Expenses Charged on Consolidated Fund: The expenses of the UPSC, including salaries and allowances of its members and staff, are charged on the Consolidated Fund of India. This means they are not subject to the vote of Parliament, further insulating the Commission from political influence.
5. Prohibition on Re-employment: The Chairman of UPSC is ineligible for further employment under the Government of India or any State Government after retirement. A member (other than the Chairman) is eligible for appointment as Chairman of UPSC or a State Public Service Commission (SPSC), but not for any other government employment. This provision aims to prevent the possibility of future favors influencing their decisions.
6. Merit-Based Selection: UPSC employs rigorous, transparent, and standardized examination and interview processes, focusing on merit and competence, thereby minimizing scope for bias or favoritism.
7. Non-Political Composition: Members are typically drawn from diverse backgrounds (academics, civil servants, jurists) and are expected to be non-political, ensuring that decisions are based on objective criteria.

Through these robust constitutional safeguards and operational practices, the UPSC has largely succeeded in maintaining its impartiality, earning a reputation as a credible and independent institution for public service recruitment in India.