[ Thanks to Martin Michlmayr
for this link. ]
“When a contribution is made to an open source project, there is
an implicit assumption (and sometimes explicit consent) that the
contribution (code, translation, artwork, etc) may be incorporated
into the project and distributed under the license the project is
using. However, many conditions of the contribution are not
explicitly called out. The purpose of Contributor Agreements is to
make the terms under which contributions are made explicit, thereby
protecting the project, the users of the software and often also
the contributors.“Apache Software Foundation (ASF) describes the aim of their CLA
in this way: ‘The purpose of this agreement is to clearly define
the terms under which intellectual property has been contributed to
the ASF and thereby allow us to defend the project should there be
a legal dispute regarding the software at some future time.’
Contributor Agreements also ensure that contributions cannot be
withdrawn by the contributor, as the FAQ for the Django CLA
explains: ‘The CLA also ensures that once you have provided a
contribution, you cannot try to withdraw permission for its use at
a later date. People and companies can therefore use Django,
confident that they will not be asked to stop using pieces of the
code at a later date.'”