TRADITION VS SCHOLARSHIP
The answer
On the New Perspective reading — Dunn's especially — "works of the law" points at the practices that marked Jews off from Gentiles: circumcision, food laws, Sabbath. The older reading, human effort to earn God's favor, is still defended in print. Same Greek phrase, two live readings.
Why it’s interesting
Which reading you take changes what Galatians is about: a fight over earning salvation, or a fight over who can share a table. Galatians 2 itself unfolds around a withdrawn meal at Antioch.
Genuinely debated
You can know the Bible.
Not just the stories, but the history, authorship, and scholarship behind it.