We illustrate a formalization of data usage policies in a fragment of OWL2.  It can be used to encode (i) a company's data protection policy, (ii) data subjects' consent to data processing, and (iii) part of the GDPR (the forthcoming European Data Protection Regulation).  Then a company's policy can be checked for compliance with data subjects' consent and with part of the GDPR by means of subsumption queries.  We provide a complete and tractable structural subsumption algorithm for compliance checking and prove the intractability of a natural generalization of the policy language.