In propria persona

Pro se legal representation (/ˌproʊ ˈsiː/ or /ˌproʊ ˈseɪ/) comes from Latin, literally meaning "on behalf of themselves", which basically means advocating on one's own behalf before a court, rather than being represented by a lawyer. This may occur in any court proceeding, whether one is the defendant or plaintiff in civil cases, and when one is a defendant in criminal cases. Pro se is a Latin phrase meaning "for oneself" or "on one's own behalf". This status is sometimes known as propria persona (abbreviated to "pro per"). In England and Wales the comparable status is that of "litigant in person".

According to the National Center for State Courts 2006 report, in the United States, many state court systems and the federal courts are experiencing an increasing proportion of pro se litigants. Estimates of the pro se rate of family law overall averaged 67% in California, 73% in Florida's large counties, and 70% in some Wisconsin counties. In San Diego, for example, the number of divorce filings involving at least one pro se litigant rose from 46% in 1992 to 77% in 2000, in Florida from 66% in 1999 to 73% in 2001. California reports in 2001 that over 50% of family matters filings in custody and visitation are by pro se litigants. In the U.S. Federal Court system for the year 2013 approximately 27% of civil actions filed, 92% of prisoner petitions and 11% of non-prisoner petitions were filed by pro se litigants. Defendants in political trials tend to participate in the proceedings more than defendants in non-political cases, as they may have greater ability to depart from courtroom norms to speak to political and moral issues.

...
Wikipedia