I'm a little confused by copyright notices on open source projects.Let's say that a particular project is covered by a very permissive license, such as MIT or BSD.  A copyright notice appears from the company that originated the source code.But let's say that the project leader leaves the company, but continues to contribute to the project.  Should s/he add a new copyright notice, to indicate that portions are copyright from the original company and portions from the author no longer employed by that company?It seems to me that anyone who touches a file essentially invalidates the copyright claims of anyone prior, because the file becomes a new creative expression based on those modifications.  How is the copyright supposed to be managed in a legally (and morally) robust manner as more and more people contribute?
Copyright and Contributing to an Open Source Project
licensing;contributor;copyright;collaboration
This is where the problem (or advantage) of multiple copyright owners comes in with open projects. There are two scenarios, based on whether a Copyright Transfer Agreement (CTA) is required to contribute to the project.If a CTA is required to make contributions, then the issue is moot as the organization running the project becomes the copyright holder.Otherwise, a common practice is to have multiple copyright lines within each affected file.Thus you might see the following:// Copyright 1998..2015 Myorganization// Copyright 2013 Fred Coder// Copyright 2011 A N OtherIndicating that the file has been modified throughout its life by the official 'organization', but has also been touched by two different developers.The copyright in this case exists in the entire file, as a combination of all contributions, rather than in specific lines of code.Another approach is to have a single file (often named something like  CONTRIBUTORS.txt) in the project root which identifies everyone who has some copyright claims to the source code.