Jason Albert said he disagrees with opponents of copyright that argue it has become irrelevant in the digital age.
"Copyright is a very flexible tool that enables a wide variety of economic activity," he told Managing IP in an interview.
But he added: "There is no question that the law continues to evolve in the light of technology."
Albert pointed to the DMCA and the European E-Commerce Directive, which were passed in the late nineties, soon after the 1996 WIPO Copyright Treaties.
Just over a decade on, with the growth of digital technology, the internet, file-sharing and rapid communication, there are again calls for fundamental reviews of the copyright system.
At a WIPO meeting last month, Lawrence Lessig proposed that the Organisation establish a Blue Sky Commission to examine whether the global copyright system is working and how it needs to be reformed.
Meanwhile, in both the UK and Ireland, reviews are underway that will address the purpose of copyright in a digital economy. Initiatives such as Google Books have also challenged the principles of copyright.
Albert, who also spoke at the WIPO conference in a panel on software - tailoring licences to markets - told Managing IP that "copyright has a key role to play" in promoting economic growth. "The great thing about copyright is its flexibility: the creators of works can license their works to meet their economic objectives," he explained.
In software, this can encompass both proprietary and open source models, said Albert. He cautioned: "In a world without copyright, the value goes to the aggregators and packagers, not the creators."
He also said that copyright plays a distinct and complementary role to patent protection in the software industry: "Both are very important. Copyright protects the expression of code, which enables licensing, while patents can protect the inventive idea."
He added that copyright protection would drive growth in IT services in developing markets - not just India and China, but other smaller countries in Asia, Latin America and Africa.
Microsoft estimates that from 2009 to 2013 developing countries will account for 70% of new IT jobs and 60% of new companies. China is about to become the world's largest PC market.
Growth in local businesses will in turn lead to greater efforts in tackling software piracy, he predicted. According to the Business Software Alliance, piracy rates in many developing countries are higher than 90%.
Albert acknowledged however that copyright will have to evolve to meet new challenges. He said Microsoft would be likely to participate in the reviews underway and he noted that "cooperative initiatives" are being discussed, such as a global database of registries of copyright works and a mechanism to improve access for blind people.
In his speech, Albert emphasised that copyright enables a "mixed-source world" in software, in which there is a place for both proprietary and open source models.
Questioned by Managing IP, he rejected the view that open source will become predominant, saying: "Each model has its place. You need a model that drives economic growth."
