Bob is underage, yet commits a severe criminal act that's worthy of going to trial. Normally, one is allowed to represent themselves in court, however ill-advised that may be. But is Bob, underage as he is, allowed that same right?
Feel free to set the age/crime to be whatever such that Bob would appear in court underage.
The Supreme Court has affirmed the constitutional right to self-representation in Faretta v California, but in Godinez v. Moran, the court injected the logically prior question of competence, rejecting a mixed-bag approach to competence. The court held that
when a defendant seeks to waive his right to counsel, a determination that he is competent to stand trial is not enough; the waiver must also be intelligent and voluntary before it can be accepted. While States are free to adopt competency standards that are more elaborate than the Dusky formulation, the Due Process Clause does not impose them.
The specific issue in this case is competence to plead guilty. In Indiana v. Edwards, the court stated that there is no absolute right to self-representation if one is competent to stand trial. It is held that
The Constitution does not forbid States from insisting upon representation by counsel for those competent enough to stand trial but who suffer from severe mental illness to the point where they are not competent to conduct trial proceedings by themselves.
One conclusion to be drawn from this is that states may but are not required to insist on a specific competence to self-represent, so there can be multiple standards of competence. Second, the Edwards court put the issue more in the realm of questions of insanity, where the limit imposed on a technical minor would have to be a substantial finding of incompetence, and not just a statutory declaration that anyone below the age of 18 is ipso facto incompetent to legally defend themselves but they can be competent to stand trial.
In Martinez v. Court of Appeal of California, the court further held that nothing "requires a State to recognize a constitutional right to self-representation on direct appeal from a criminal conviction".
This study indicates that individual states have not eagerly cleared the path to minor self-representation, noting that "Many states permit waiver by a juvenile after cursory inquiry by the court", but "Others require that the juvenile consult with a parent, lawyer or other adult". Nevertheless, "waiver of counsel is, almost without exception, connected to an 'admission,' or guilty plea", simply asserting that "Juveniles do not represent themselves at trial", and what minors waive is the right to trial. There is a lack of relevant case law citations in this study, in that no ruling is cited where the court affirms that minors are automatically incompetent to represent themselves in a criminal trial. The specifics of the qualifier "almost without exception" would be very relevant to this question.
Assuming Bob is above the age of criminal responsibility, it appears that he could not act as a Litigant in Person (know as pro se is the USA).
Although there is no statutory bar to the contrary (that I can find, but I'm still working on it) my reading of the Judicual College's Equal Treatment Bench Book at Chapter 1: Litigants in Person and Lay Representatives where it says...
12 ...everybody of full age1 and capacity is entitled to be heard in person by any court or tribunal...
... means that those not yet at "full age" are excluded - but it's difficult to prove a negative.
Note that the Equal Treatment Bench Book says at paragraph 2 of its Introduction, on page 5, although it ...
... does not express the law, judges are encouraged to take its guidance into account wherever applicable. It is increasingly cited in judgments and by practitioners as to the approach to be adopted.
So, as I say, I will keep looking for legislation to provenance this judicial guidance.
1 For clarity: "full age", also known as the age of majority, is 18 years old and defined by section 1(1), Family Law Reform Act 1969:
...a person shall attain full age on attaining the age of eighteen...
Generally, yes: an accused young person (a person twelve years old or older, but less than eighteen years old) who is fit to stand trial has the right to represent themself.
While an accused young person has the right to counsel, as well as access to legal-aid or state-funded counsel (see Youth Criminal Justice Act, s. 25), they cannot be forced to be represented by counsel unless the court is not satisfied that the accused understands (1) the charges, (2) consequences of an adult sentence (if applicable), and (3) the election between a judge-alone trial and a judge-and-jury trial (see s. 32).
yet commits a severe criminal act that's worthy of going to trial
This implies that the case is held in front of the Jugendstrafgerichtskammer. Because it is a criminal court, you will are required to be given a Pflichtverteidiger (Defense attorney) according to § 140 StPO. Atop that, this is in front of the Jugendgericht, so § 68 JGG applies, reiterating that when prosecuting a youth for a crime that requires a Pflichtverteidiger for adults, the youth has to be given one, but adds other cases where the minor gets an attorney on court mandate.
Now, while §140 (1) StPO only demands the defendant to get an attorney to assist their defense while mostly representing themselves, $140 (2) StPO is there to force the attorney to do everything in case:
(2) Ein Fall der notwendigen Verteidigung liegt auch vor, wenn wegen der Schwere der Tat, der Schwere der zu erwartenden Rechtsfolge oder wegen der Schwierigkeit der Sach- oder Rechtslage die Mitwirkung eines Verteidigers geboten erscheint oder wenn ersichtlich ist, dass sich der Beschuldigte nicht selbst verteidigen kann.
(2) In all other cases, the presiding judge shall appoint defence counsel upon application or ex officio if the assistance of defence counsel appears necessary due to the severity of the offence, due to the difficult factual or legal situation, or if it is evident that the accused cannot defend himself.
(from the somewhat outdated english version)
In Germany, it is general consensus, that a person below 18 can not effectively defend themselves without assistance, and that even a person up to 21 can be treated as a youth in front of the court. For this, the Jugendgerichtshilfe will evaluate if they are to be treated as an adult between 18 and 21. While a youth between 14 and 18, it is nigh impossible to be allowed to defend yourself alone. While the accused has technically the right to speak and make injections, the younger they are the more the court will lean to the side that they are not mentally in the capacity to understand everything happening and request the lawyer to take extra steps to make sure the defendant doesn't hurt their own case. Older people tried at the Jugendgericht will only have mandatory assistance in a court-appointed lawyer to explain things and try to inform them of rights and duties and assist as needed - which can start at assisting in filings up to taking over the defense fully.
Not only can children represent themselves, in the US, thousands have had to represent themselves in deportation trials without the option to have a lawyer. https://www.hrw.org/news/2016/03/14/us-children-face-deportation-without-lawyers
Specifically, there have been 3 year olds who have had to (very unsuccessfully) represent themselves in court.
