Protection is an essential issue for the kind of heterogeneous distributed interoperable object environments, which Java and CORBA are a glimpse of. A uniform protection mechanism such as capabilities, integrated with the object model of the system is a good and flexible solution for these environments. Oviedo3 is an example of an Integral Object-Oriented System (IOOS) based solely on the OO paradigm, developed OO Abstract Machine (OOAM) and OO Operating System (OOOS). When integrated with the odel of the abstract machine, capabilities gain new advantages such as automatic protection. Capabilities also allow more flexible security policies. Existing platforms such as Java, without an uniform protection mechanism, could be made more suitable for these new environments by applying these benefits.