stick up, v.³ — Green’s Dictionary of Slang

stick up v.³

to hold one’s ground in an argument.

1890–1904

stick up to (v.)

to challenge, to oppose, esp. when one is ostensibly at a disadvantage.

1864, 1867, 1870		Hotten Sl. Dict.
1902		H. Baumann Londinismen (2nd edn).
1937–84		Partridge DSUE (1984) 1153: [...] coll.: from ca. 1840: dial. till ca. 1860, then coll.