## 6 Unifying Semantic Legal Policies
### A Peer Registers at a TLD  
A peer \(p_{i}\) should register at the \(\mathit{sp}_{\alpha}\) before this peer can offer its data for integration in an \(\mathit{SPD}_{\alpha}\), This registration action implies that \(p_{i}\) pledges to obey the privacy protection law by applying specifications of the data usage context declared in the \(\mathit{sp}_{\alpha}\).  
Based on this data usage context specification, \(p_{i}\) uses the LAV source description to export its data to \(\mathit{sp}_{\alpha}\) for data integration. Peer \(p_{i}\) also registers at another \(\mathit{SPD}_{\beta}\), shown as \(\mathit{TLD}_{\beta}\) and exports its data for national security policy enforcement purposes. This indicates that the laws from \(\mathit{sp}_{\alpha}\) and \(\mathit{sp}_{\beta}\), which are privacy projection and national security legal policies, respectively, are unified and enforced after collecting data from \(p_{i}\).  
An open cloud is sometimes constructed as a virtualization-layered architecture for multi-tenant services. A peer is a virtual node within an SPD, and corresponds to a database installed in virtual machines (VMs). We might face a situation, where a database is compliant with a data protection law \(\alpha\) from one jurisdiction but a data center providing VMs to host the database is compliant with a national security law \(\beta\) from another jurisdiction. This multi-tenant cloud service layout is different from that of Gmail and Facebook, where the cloud management services of data centers and databases belong to a single legal authority.  
One possible solution to this legal discrepancy is to enact a service level agreement (SLA) between owners of a database and a data center before the database is installed in the data center's VMs. The SLA provides the necessary information for a database owner to ensure that he/she is aware of this legal domain discrepancy. Another possible solution for preserving privacy in data outsourcing is to enforce privacy over data collections by combining _data fragmentation_ with _encryption_ to avoid illegal data usage requests from _curious but honest_ cloud providers [31]. For more details, see Section 7.1. Unless national security law enforcement officers comply with the SLA and national security laws, any data disclosure request made without a data owner's prior consent will be rejected.  
Figure 5: A data request uses its own data usage context to decide which super-peer to contact. Each super-peer binds a type of law for data access control in its SPD. For example, \(\mathit{agent}_{\alpha}\) at the \(\mathit{sp}_{\alpha}\) uses the data protection law in \(\mathit{TLD}_{\alpha}\) and \(\mathit{agent}_{\beta}\) at the \(\mathit{sp}_{\beta}\) uses the national security law in \(\mathit{TLD}_{\beta}\). Finally, a query for data exchange, abode by \(\mathit{agent}_{\alpha\cap\beta}\), is by unifying laws at the \(\mathit{sp}_{\alpha\cap\beta}\) in \(\mathit{TLD}_{\alpha\cap\beta}\).  
Based on the above proposition, we propose a solution by unifying legal policies submitted by different judicial authorities. On the one hand, when an end-user requests for data exchange from the _TLD\({}_{\alpha\cap\beta}\)_, two types of legal policies, e.g., privacy protection and national security, from different judicial domains are unified to legally restrict data exchange access at \(p_{i}\). On the other hand, when an end-user requests data from _sp\({}_{\alpha}\)_ or _sp\({}_{\beta}\)_ separately, we do not unify legal policies in this situation; therefore, one type of law is applicable for a data request.