A probation condition governing a defendant’s conduct need not be based on actual knowledge to avoid a vagueness challenge—the term may reference constructive knowledge as well. Mendez was placed on Proposition 36 probation for possession of cocaine. One term of his probation prohibited his association with persons “you know or have reason to know” are drug users, probationers, or parolees. At sentencing (and on appeal) his attorney objected to the “reason to know” language of the condition, claiming actual knowledge was constitutionally required to avoid the term being vague. Held: Affirmed. The Supreme Court in In re Sheena K. (2007) 40 Cal.4th 875 affirmed that a probation term must be sufficiently precise to alert the probationer of what is expected of him, although it did not address whether the required knowledge could be constructive as well as actual. Opinions after Sheena K. have modified challenged probation terms to add an express constructive knowledge element. In addition, the California Legislature has used the “reasonably should know” standard in defining a number of criminal offenses. There is nothing unconstitutionally vague about a penal statute containing a constructive knowledge requirement. Similarly, there was nothing vague about the “reason to know” language of Mendez’s probation term.