You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Copyright_infringement

Context:
In order to qualify for protection, a work must be an expression with a degree of originality, and it must be in a fixed medium, such as written down on paper or recorded digitally. The idea itself is not protected. That is, a copy of someone else's original idea is not infringing unless it copies that person's unique, tangible expression of the idea. Some of these limitations, especially regarding what qualifies as original, are embodied only in case law (judicial precedent), rather than in statutes.

Question:
What limitation is only embodied in case law, rather than statues?

what qualifies as original