The legal context of 'volens' has already been thrashed out here before,
http://wordsmith.org/board/showthreaded.pl?Cat=&Board=words&Number=91872
...but my interest was willingly solicited by this saying and I wondered whether any of you know or use it.

Although m-w.com provides a definition of 'nolens volens', the phrase is clearly not in widespread usage. And yet the concept it reflects is a very common one. The notion of a person being 'willing-unwilling' drawn into singing a song, or dancing, etc. is quite useful, I think. Sure there are plenty of alternatives - but it has a good rind to it, does it not?

"...halb zog sie ihn, halb sank er hin" Goethe - Der Fischer