BigQuery customers previously relied on policy tags for column-level security of sensitive data. However, the evolving complexity of data ecosystems required more robust solutions. Google Cloud is now introducing data governance tags in BigQuery, built on IAM's Resource Manager infrastructure. These tags offer a scalable and powerful method for managing access controls and protecting column data. Data governance tags have a global scope, unlike regional policy tags, allowing for organization-wide application. They also support managed disaster recovery, with security policies automatically replicating to secondary regions. A key feature is hierarchical security, enabling up to five levels of granular data classification. This decoupled governance approach allows data tagging before access enforcement, providing flexibility. To implement column-level security, one must first create data governance tag keys and values, specifying the purpose as DATA_GOVERNANCE. Next, tags are attached to BigQuery columns via JSON schema updates or SQL statements. Finally, regional data policies are created to govern access to these tagged columns, either revealing raw data or masked versions. This layered security ensures that only authorized users with appropriate base table access can view sensitive information.