The tag is present in Lintian version 2.104.244. That is the most recent version we know about.
Every package must include the file
A copy of this file should be in
debian/copyright in the source package.
These sources ship a copyright file named according to debhelper convention
debian/$package.copyright but build only one installable. Please move
the copyright file to
Refer to Debian Policy Manual section 12.5 for details.