The law was not meant to provide a means of justification - or was it?

Galatians 3:21 is used to prove that God never intended the law to be a means of justification. I think this is squeezing more theologial jus out of the text. Of course life cannot come by that law, given that humans are all sinful. But does that mean that the law did not offer justification and therefore life to any who could, theoretically, keep it perfectly?

Taken on its own, in isolation from broader salvation history, the law does indeed offer a means for justification. It never succeeds, because no individual can keep it, but the offer is real.

The argument in Galatians 3:15ff is:

1. This offer does not set aside the previous offer of righteousness by faith.
   
2. The failure for the law to deliver righteousness doesn't mean it was useless - it served to expose sinfulness.