Code ownership is a smell, and we need to avoid it. When several developers contribute to the same codebase, several great minds are thinking of the same problem, which eventually results in a better solution. On the opposite side of the spectrum, with strong code ownership, you inevitably end up with code that is easier to rewrite than to understand by others.

I took this for granted until I came across Microsoft research that contradicted my common sense. They showed that code ownership results in higher code quality and fewer bugs.

Code ownership and software quality

That the more engineers modify a file, the higher the number of bugs that are linked to this file and that if there is one primary contributor, the chances for a file to be buggy decreases significantly.

Looking further, I found out that researchers and practitioners went to both extremes. There is more to read at https://wiki.c2.com/?CodeOwnership.

I wish I could culminate this post with an elegant theory or at least a rule of thumb that would embrace both points of view, but nothing beyond a helpless “it all depends” and “the truth lies somewhere in between” comes to mind. I keep this question open for myself.