To what extent does copyright protect software functionality?
<p>Suppose I see an innovative piece of (commercial) software that delivers considerable, non-trivial functionality.  </p>

<p>Can I re-implement it?  Suppose I study it carefully, work out what it does and how it does it, and then write my own software to do the same thing.  I haven't (knowingly) copied any specific part of that system, but I have replicated the system as a whole ...its design.  So have I infringed the copyright of the original system?  </p>

<p>Consider the possibility of translating a Harry Potter novel into French.  If I change the names, I could produce a text that didn't contain a single word of Rowling's original. But I believe that doing so would infring Rowling's copyright.  What is the situation with software?</p>

<p>You can't compare a novel and a computer program that way. With a novel, the expression and the essence of the work are the same. With a computer program, while the expression is hard work to create, and often is very original, the essence of the work is what it does. </p>

<p>So I can create a totally independent computer program doing the exact same thing, without any copying whatsoever. With your novel, the essence of the work is copied. Unless you change Harry Potter to a pot smoking sanitary engineer, change his wand to a guitar, move him to a different world, where is not surrounded by fellow wizards but by intelligent, speaking animals, and write the whole thing a few years before Mrs. Rowling did. </p>

copyright intellectual-property software