Which of the following is an incorrect step in derivative classification?

Classifying information based solely on individual judgment is indeed an incorrect step in the derivative classification process. This practice undermines the established protocols for determining classification levels and can lead to inconsistent and potentially unauthorized classifications. The derivative classification process relies on objective criteria set forth in official guidelines, including Security Classification Guides (SCGs) and existing classified documents, which provide a framework for making classification decisions.

Relying solely on personal judgment disregards these important guidelines, which are designed to ensure that classification decisions are made consistently and based on standardized criteria rather than subjective opinions. Therefore, derivative classifiers must always use established references and the appropriate classification markings to maintain the integrity of the classification system.

The other choices reflect accepted practices in derivative classification. Making an initial determination of protection against unauthorized disclosure is a fundamental step in safeguarding classified information. Using a Security Classification Guide provides a necessary framework for classifying information correctly, and defining classifications based on existing classified documents ensures continuity and consistency in the classification process.