* Research Misconduct: This is the most common reason. It includes plagiarism (significant, not just minor instances), fabrication or falsification of data, and image manipulation in publications used to fulfill the dissertation requirements. The misconduct must be demonstrably intentional and not simply a matter of error or oversight. The severity and impact of the misconduct are crucial factors. A single minor error is unlikely to lead to revocation; widespread or deliberate falsification is more likely.
* Academic Dishonesty Beyond Research: While less common, severe cases of plagiarism in other aspects of the PhD program, such as in coursework or qualifying exams, could theoretically lead to revocation, especially if coupled with research misconduct.
* Fraud in Application or Admission: If it is discovered that the candidate obtained admission through fraudulent means (e.g., falsifying transcripts, fabricating letters of recommendation), the university might revoke the degree.
* Breach of University Regulations: This is a less frequent reason and usually involves very serious violations of university policy that directly relate to the academic integrity of the degree itself, such as severe breaches of conduct that compromise the integrity of the research process.
Important Considerations:
* Burden of Proof: The university carries a heavy burden of proof to demonstrate beyond a reasonable doubt that the misconduct occurred and warrants revocation. This often involves a thorough investigation and potentially a formal hearing.
* Due Process: The candidate is entitled to due process, including the opportunity to present their case and challenge the university's findings.
* Time Limits: There are often time limits on how long after the degree is awarded the university can initiate revocation proceedings.
* Differing Policies: The specific procedures and policies regarding degree revocation vary significantly between universities and countries.
In summary, while theoretically possible, PhD revocation is an exceptional circumstance reserved for egregious cases of academic dishonesty or fraud that significantly undermine the integrity of the research and the degree itself. Minor errors or unintentional mistakes are generally not grounds for revocation.