Which is, unfortunately, completely useless when it comes to copyright infringement. Trust in the individual will not change the output of an audit for copyrighted code, or the results from said audit.

The only thing that a "trusted" individual can contribute in a copyright infringement investigation is attesting that they did not know that the code they put in the codebase was copyrighted. And all that does is save the company from getting the higher "willful infringement" fines, if it should get that far.

Wilful Infringement Damages: https://www.ce9.uscourts.gov/jury-instructions/node/708

Significant enough that if the license is GPL (which some has been) it will "taint" the entire codebase and license it under GPL. Significant enough to be found by automated OSS audit tools, which would trigger a re-write and education for the developer who committed it.

EDIT:

> If I write down lyrics I remember I still wrote it.

Not from a copyright point of view. The rights to those lyrics belong to the songwriter. It's kinda like photographs. You don't automatically have the right to distribute a photograph of yourself that was taken by someone else.