diff --git a/TODO b/TODO
index 2c6c0bd..528c9c0 100644
--- a/TODO
+++ b/TODO
@@ -62,3 +62,44 @@ Other interesting package managers
 Windows
 ----------
 Try running Urchin in Windows somehow. I guess CygWin.
+
+Consider copyleft licenses
+----------
+ScraperWiki owns the original version of Urchin (Thomas Levine did the early
+work as part of his work for ScraperWiki.) and originally licensed it under an
+MIT-style license. Other people made changes after this original ScraperWiki
+version. As of January 2016, they are just Thomas Levine (when he wasn't
+working for ScraperWiki) and Michael Klement.
+
+The original license was MIT just because that's what ScraperWiki put on
+everything. Should we change the license?
+
+The MIT-style license grants pretty much all rights. It says that you need
+to attribute when you redistribute source code, but you don't
+necessarily have to redistribute source code.
+
+A copyleft license adds the restriction that modified versions of the
+code need to be licensed under the same license. GNU licenses in
+particular require that source code be released if non-source versions are
+released, and the different GNU licenses differ in what how the
+non-source version is defined. (The original, GPL, discusses compiled
+binaries.) Copyleft doesn't mean anything specific for commercial use.
+
+MIT-licensed code can be modified and then licensed as GPL, because MIT
+license allows that, but GPL code can't be modified as MIT, because MIT
+doesn't allow that. And if we get all of the authors to agree on it, we
+can always add whatever crazy license we want, regardless of what we
+have already.
+
+The distinction between MIT-style and GNU-something might matter quite little
+in the case of Urchin.
+
+1. Urchin is written in an interpreted language (shell), so it might be
+   hard to distribute usefully without providing the source code.
+2. Urchin just runs tests; it doesn't get compiled with the rest of the
+   code (also because it's in shell). Thus, I think a GPL license on
+   Urchin wouldn't infect the code being tested.
+
+This is as far as I have gotten with contemplating license changes. For now
+we're sticking with the original MIT-style license, but it's easy to change
+licenses later.