OSC's primary mission is the safeguarding of the merit system in federal employment by protecting employees and applicants from prohibited personnel practices (PPPs), especially reprisal for "whistleblowing."

OSC enforced restrictions against prohibited personnel practices and unlawful political activity by filing, where appropriate, petitions for corrective and/or disciplinary action with the Board.

Congress enacted legislation in 1993 that significantly amended Hatch Act provisions applicable to federal and District of Columbia (D.C.) government employees, and enforced by OSC.

Under the new law, state and local government employees are no longer prohibited from running for partisan office unless their salary is paid for completely by federal loans or grants.

[6] According to congressional testimony by Tom Devine, legal director of the non-profit Government Accountability Project: The Watergate investigation of the 1970s revealed a Nixon administration operation to replace the non-partisan civil service system with a politically loyal workforce dedicated to partisan election goals.

Then-White House Personnel Office chief Fred Malek teamed up with Alan May to prepare the "Malek Manual," a guide to exploiting loopholes in civil service laws to drive politically undesirable career employees out of government and replace them with applicants selected through a political rating system of 1–4, based on factors such as campaign contributions and future campaign value.

Though not as productive as it could have been, as a young agency in 1979, the Office of Special Counsel filed two requests for corrective action with the Merit Systems Protection Board.

In Tariela and Meiselman, two high-level Department of Veterans Affairs employees were threatened with reassignment for disclosing violations of laws, rules, and regulations.

Devine added: He used its techniques to purge the professional civil service experts on his own staff, and replace them with employees who viewed whistleblowers as crazy troublemakers disloyal to the President.

"Devine also testified that: Mr. Kozinski's abuses were the major catalyst for passage of the Whistleblower Protection Act of 1989, and he was forced to resign.Under the WPA, the Office of Special Counsel became an independent agency.

"[10] In 2002, the Office of Special Counsel announced a program to help federal agency heads meet the statutory obligation to inform their employees about the rights, remedies, and responsibilities of the Whistleblower Protection Act under 5 U.S.C.

"[11] From 2005 to 2007, OSC under Special Counsel Scott Bloch received disclosures regarding air traffic control problems at the Dallas/ Fort Worth International Airport.

"[12] In 2006, the Office of Special Counsel announced that it was able to win reemployment and back pay for an injured Iraq war veteran who "sustained serious injuries in the line of fire."

[13] The agency attracted public attention in April 2007 when it began an investigation of alleged White House political pressure on federal civil servants.

It was alleged that when Bloch's refusal to follow up on cases of discrimination based on sexual orientation was leaked to the press, he retaliated against career employees by creating a field office in Detroit.

Senator Daniel K. Akaka (Democrat, Hawaii), Chairman of the Subcommittee on Oversight of Government Management, the Federal Workforce, and the District of Columbia, held a hearing on "Safeguarding the Merit System Principles."

[25] In July and October 2011, OSC requested and obtained stays from the MSPB in three whistleblower retaliation cases—those of David Butterfield of the Department of Homeland Security, Franz Gayl of the U.S. Marine Corps and Paul T. Hardy, a member of the U.S. Public Health Service.

[26][27] On a matter related to the case of Franz Gayl, OSC filed an amicus brief in October with the MSPB, arguing that the Board should afford greater due process protections to employees who are suspended without pay because of the suspension of a security clearance.

[29][30] Lerner sent draft legislation to Congress, proposing changes in the enforcement structure, an end to the prohibition on state and local candidacies linked to federal funding, and other changes.

It modified penalties under the Hatch Act to allow for disciplinary actions in addition to removal for federal employees and clarified the applicability to the District of Columbia of provisions that cover state and local governments.

[32] The Office of Special Counsel continue to receive numerous disclosures from FAA employees, including air traffic controllers, regarding ongoing safety concerns at United States airports.

[33] In April 2011, the Office of Special Counsel entered into a three-year "Demonstration Project" with the U.S. Department of Labor to enforce the Uniformed Services Employment and Reemployment Rights Act (USERRA), which, according to the Office of Special Counsel, "prohibits employment discrimination against veterans and members of the National Guard and Reserve and entitles them to reinstatement in their civilian jobs upon their return from military duty."

According to a letter Special Counsel Lerner sent to President Obama, "These whistleblower disclosures are the latest, and most severe, in a persistent drumbeat of concerns raised by seven Jackson VAMC employees to OSC in the last four years.

Even in cases of substantiated misconduct, including acknowledged violations of state and federal law, the VA routinely suggests that the problems do not affect patient care."

According to an Office of Special Counsel press release, "The complaints charge two of the three CBP officials with discriminating in favor of political appointees and against other potential candidates.

[41] In 2018, OSC said that counselor to President Trump, Kellyanne Conway, violated the Hatch Act when she made political remarks regarding the 2017 Alabama Senate election on two different occasions.

In 2024, Hampton Dellinger was appointed as head of the Office of Special Counsel by President Joe Biden and confirmed by the Senate to a five-year term.

[44] Afterwards, Dellinger opened a lawsuit, arguing that Trump acted beyond his legal authority by firing him before the end of his term[44] and without citing issues with his performance.

[43][44] On February 16, the Justice Department opened an emergency appeal with the Supreme Court seeking to lift the temporary order, arguing that it is an unacceptable intrusion on executive power,[43][46] after the D.C.