Java belongs to Sun/Oracle.
The trademark "Java" belongs to Sun/Oracle. I believe that anyone who wants to implement a compiler and tool set for the JLS/JVM/JRE is free to do so as long as it's not called "Java". (Note that Oracle's lawsuit against Google is not about implementing the Java language, but about patents allegedly infringed in the process.)
The JLS may be copyrighted (meaning, the document itself), but it is freely available.
I know Microsoft lost a lawsuit to Sun for producing J# with class lib incompatible to java lang spec.
The lawsuit wasn't about J# (which is a .Net language), but about Microsoft's Java implementation (the
IDE for which was called Visual J++). They licensed the Java trademark from Sun under the condition that their implementation would be faithful to the JLS and class libraries - which it wasn't.