analyze Rule 23’s prerequisites before certifying a class.” Spence v. Glock, Ges. m.b.H,, 227 F.3d 308, 310 (5th Cir.2000) (internal citation omitted). This requires an understanding of “the relevant claims, defenses, facts, and substantive law pre sented in the case.” Allison, 151 F.3d at 419 (citing Castano v. Am l on the merits would be conducted if a class were certified.” Bell All., 339 F.3d at 302 (internal citations omitted). When there are disputed facts relevant to Rule 23 requirements, overlap with the merits “should not be tal when the Supreme Court later observed in Wal-Mart Stores, Inc. v. Dukes that rigorous Rule 23 analysis frequently will “entail some overlap with the merits of the plaintiffs underlying claim.” — U.S. —, 131 S.Ct. 2541, 2551-52, 180 L.Ed.2d 374 (2011) (<HOLDING>). The Supreme Court in Wal-Mart noted that in
holding that while the certifying court should not make any factual findings or merits determinations that are not necessary to the rule 23 analysis  where merits issues cannot be avoided they must be addressed holding certification is not an occasion for inquiry into the merits holding that where proof of commonality necessarily overlapped with the merits contention that defendant had engaged in a pattern or practice of discrimination inquiry into that merits contention was appropriate for rule 23 analysis recognizing that sanctions are collateral to the merits of the case and may be considered even after the merits are no longer before the district court holding that a district court must give full and independent weight to each rule 23 requirement regardless of whether that requirement overlaps with the merits