Can I speak for myself in a federal court, without a lawyer?
Answered for: Federal courts
In all courts of the United States the parties may plead and conduct their own cases personally or by counsel as, by the rules of such courts, respectively, are permitted to manage and conduct causes therein.
The federal statute says the parties may plead and conduct their own cases personally. It also says this happens as the rules of each court permit, so the individual court's rules still apply.
This answer is true in Federal courts and nowhere else on this site. Another jurisdiction is another answer, or an honest gap: see what has been read for Federal courts.