The Texas declaratory judgment statute can allow the recovery of attorneys fees. Tex. Civ. Prac. & Rem. Code § 37.009. The federal statute, 28 U.S.C. § 2201 et seq., does not. Utica Lloyds v. Mitchell, 138 F.3d 208 (5th Cir. 1998).
The starting point for review of evidentiary sufficiency in the Fifth Circuit is Boeing Co. v. Shipman, 411 F.2d 365 (5th Cir. 1969) (en banc). The starting point for an analysis of legal sufficiency of the evidence in Texas state court is City of Keller v. Wilson, 168 S.W.3d 802 (Tex. 2005), which also discusses a review for factual sufficiency. (The distinction between “legal” and “factual” sufficiency review is unique to Texas procedure, and flows from a limit placed by the Texas Constitution on the jurisdiction of the state supreme court.)
In Texas, the problem of appellate review for jury submissions that mix valid and invalid legal theories is addressed by a line of cases named for Crown Life Ins. Co. v. Casteel, 22 S.W.3d 378 (2000). The Fifth Circuit does not have such a seminal case, but a good summary of its analytical framework appears in footnote 4 of Wellogix, Inc. v. Accenture, LLP, 716 F.3d 867 (5th Cir. 2013), and McCaig v. Wells Fargo Bank (Texas), N.A., 788 F.3d 463, 476 (5th Cir. 2015) (quoting Muth v. Ford Motor Co., 461 F.3d 557, 564 (5th Cir. 2006)).
Texas Rule of Civil Procedure 202 allows a pre-suit deposition upon a proper showing; the Dallas Court of Appeals recently addressed those standards. The Federal Rules do not have a comparable provision.