Capitalize "Congress"

Warning²Federal courts, Illinois courts21st and 22nd editions

The national legislature's name is a proper noun and always takes a capital; only the adjective built from it, "congressional," stays lowercase.¹

1. 1R. 8(d)(i) Nouns that identify specific persons, officials, groups, government offices, or government bodies; R. 8(c)(i) Nouns that identify specific persons, officials, groups, government offices, or government bodies.
2. 2A warning: the form is usually wrong under the rule in note 1, and context can justify it.