= on one's own behalf. The phrase is two words, and should not be hyphenated. Functionally, the phrase may be either adjectival or adverbial. Here it is the former:
“Petitioner's response did not show cause why this court should not limit his ability to file pro se actions and papers in this court.”
Franklin v. State, 25 So.3d 645, 645 (Fla. Dist. Ct. App. 2009).
Just as frequently it is adverbial, as here:
“Father appeals pro se and argues that his incarceration has resulted in a substantial change in his income, and therefore, he is entitled to a reduction of his child-support obligation.”
In re Paternity of E.C., 896 N.E.2d 923, 924 (Ind. Ct. App. 2008).
Garner’s Dictionary of Legal Usage, Bryan A. Garner