Reviewing upstream packages to write debian/copyright files is tedious manual work. It tends not to get done again after initial packaging, especially not on every release (when something may have changed).

Making initial copyright file construction, and subsequent review/update easier will improve Debian's software quality.

Stretch (Debian 9) has significantly improved tools over previous releases.

licensecheck from licensecheck (and older versions of devscripts) can scan source code and report found copyright holders and known licenses.

scan-copyrights from libconfig-model-dpkg-perl can update an existing copyright file from rescanning the source. It can also create one from scratch. It uses licensecheck.

Config::Model can update Debian copyright files using the cme command (from cme or libconfig-model-dpkg-perl less than 2.063):

cme update dpkg-copyright

A script from cdbs can generate a copyright file using licensecheck:

licensecheck --copyright -r `find * -type f` | \
  /usr/lib/cdbs/licensecheck2dep5 > debian/copyright.auto

license-reconcile compares the existing copyright with the source code and reports discrepancies.

debmake -k also compares the existing copyright with the source code and reports discrepancies.

debmake -cc generates a new copyright file from the source code.

licensee from ruby-licensee checks LICENSE files and returns known license names.

FOSSology is a open source license compliance software system and toolkit that can (in version 3.1) generate DEP5 copyright files.

Some of the above are run by check-all-the-things -f copyright.

See also