A ruling in the Kroger-Albertsons merger case will hinge on how Judge for Oregon Adrienne Nelson interprets a 1980s-era definition of the grocery industry.

On Monday, the CEOs for Kroger and Albertsons were pushed, and pushed back, over whether the two grocery retailers need to merge.

Kroger will face off with regulators over its embattled proposed merger with Albertsons – this time against Colorado Attorney General Phil Weiser.