That seems correct: whether copyright law in principle covers copyright of APIs is a question of law rather than fact.
Under questioning from Oracle lawyer Michael Jacobs, Reinhold contended that "each page of the [Java] language specification includes a copyright notice,"
"Page, 39, testified over the course of two days, claiming that Google only used elements of the Java programming language that are freely available in the public domain. But after being admonished from the bench for evasive responses to Oracle questioning, the Google CEO finally admitted that his company never obtained a license to use Java code in its own software."