Building a world governance and constitution are necessary for the effective and efficient planning, managing, and advancing of civilization, society, and humanity well being such as global elimination or prevention of conflicts, violence, abuses, hunger, diseases, poverty, inequality and injustice; for the management and distribution of world resources; for the management of world  population, for the protection and development of the environment, biodiversity, earth resources, humanity common habitat, and the evolution of earth as a whole; as best structures to manage, adapt to, and mitigate global pollution, warming, and climate change; and to provide global solutions to global problems. They are also necessary as means to advance global governance, democracy, liberty, freedom, equality, peace, harmony, prosperity, security, unity, humanitarian causes, the common goods, inclusiveness, civil rights, universal human rights, dignity, and well being and the essence of humanity. Presently, the United Nations is the most appropriate forum or institution for all nations, states, and alliances (such as African Union, European Union, Latin America Union, Mediterranean Union, and South East Asian Union) to collaborate and unite on achieving a world governance and constitution to build a better world and humanity.

Please be mindful that the petition is for a World Governance and not a World Government. A World Governance structure is nations and states collectively govern democratically (can adapt many of the  EU and EU nations and US and States structures) while a World Government is more of a central authority.

Related petition:

http://www.change.org/petitions/global-governance-for-global-community