Able to "will" himself to become inches-tall, he steals an armored car and gets captured by Captain Marvel. After serving out a prison sentence, Baker finds gainful employment as a circus freak, then decides to become an attorney. He quickly moves up the ranks to become District Attorney, fighting crime in the courts and in the streets as Tinyman.
Jack's street clothes "magically" disappear whenever he wills himself to become small, and his costume expands when he grows large again. No explanation was ever provided for the missing street clothes.
The ability to shrink down to a tiny size where he still has the powers of a full-grown man.