Reidentified

Reidentified is the past participle of reidentify, meaning to identify again after an initial identification. In data privacy and related fields, it denotes the process or outcome by which data that was previously de-identified or anonymized is linked back to identifiable individuals, or where an individual who was previously masked becomes identifiable again.

Context and usage: The term is commonly used in discussions of data sharing, health information, public datasets, and security. Reidentification can occur when anonymized data are combined with other data sources, or when weaknesses in the original anonymization are exploited, allowing a match to a specific person. It highlights the residual risk that even carefully processed data may reveal identities under certain conditions.

Risks and implications: Reidentification undermines privacy protections and can expose sensitive information such as health, financial, or personal details. It may enable profiling, discrimination, or unauthorized surveillance. Legal and ethical considerations often address reidentification risk, with requirements for risk assessment, data governance, and restrictions on use and disclosure of data.

Mitigation: Strategies to reduce reidentification risk include stronger anonymization techniques (such as differential privacy, and properties like k-anonymity and l-diversity), pseudonymization, data minimization, access controls, encryption, and secure data-handling practices. Organizations are encouraged to perform privacy risk assessments, implement layered safeguards, and continuously monitor data-sharing arrangements to balance utility with individuals’ privacy.