General comments to keep in mind while watching this trial:
1. Perjury -- Witnesses lie and exaggerate on the stand ALL THE TIME, literally in every single trial there is a witness who lies or exaggerates on the stand. Witnesses also make mistakes about the facts they testify about, and sometimes their memory is faulty and they may not remember something accurately. None of those things is perjury, and even if a witness is outright lying -- it is extremely rare for someone to be charged with perjury because most of the time the witness can explain a discrepancy in their testimony due to memory issues or misspeaking, etc.
Perjury is a crime only when the witness knowingly lies under oath and it can be proven by comparing it to a previous written or recorded statement. And usually it has to be a lie that is material to the case on an important issue. Think Mark Furman.
2. Courtroom behavior -- Each judge is responsible for the rules of decorum in their own court. Some judges do not allow any food or drink or gum, other judges allow it. If the judge allows it, it is not disrespectful to the court to eat, drink, or chew gum.
Some judges require that attorneys keep their knees and feet off counsel table, and other judges dont require it. If the judge doesn't require it, it's not disrespectful to have your knee resting on counsel table (although as a practical matter, it looks bad and unprofessional).
Some judges and courts require electronics to be surrendered before entering a court room. Some require that all electronics be turned off. Some only require that they be silenced and even allow internet and email use in the courtroom. Whatever the particular rules are, the attorneys are generally allowed to have their phones, ipads, laptops on.
Some judge allow people in the gallery to take notes, others don't.
This particular judge apparently has pretty lax rules about court room decorum. That does not mean she does not have control of her courtroom or that she is not respected. it simply means she doesn't care about those things and does not feel like the administration of justice is compromised by people eating, drinking, chewing gum, etc in the gallery.
3. Control of the witnesses/attorneys -- I've seen so many comments and questions about how a witness can be allowed to testify the way they are or how can an attorney be allowed to ask certain questions or ask to approach so many times or how can Jodi be allowed to smile at jurors or send notes to her mother, etc. The simple answer is that whether something is allowed or not there is no way to prevent it from happening in advance -- the only way to deal with it is if someone complains and gets a ruling after the fact.
The judge can only rule on things that are brought to her attention within the legal process and what she observes with her own eyes. She removed someone from the courtroom for sleeping the other day - that is something she saw herself and corrected it. If a witness is answering inappropriately, the opposing lawyer has the opportunity to make his objections and get a ruling or instruction from the judge. If that doesn't correct the problem, there's an opportunity for the lawyer to object again and get another ruling and instruction.
It would take something really egregious for a judge to hold a witness in contempt -- rudeness, interrupting, going beyond the scope of the question is not going to do it. Contempt is an extreme remedy that is reserved for behavior that cannot be cured by any other means. A judge is not going to hold a lawyer in contempt because he or she asks to approach every thirty seconds or even because he or she goes beyond the bounds of a pre-trial ruling because these things can all be solved in other ways. The last thing the judge would want to do is hold a lawyer in contempt in front of the jury or even admonish the lawyers too strongly in front of the jury because it could be prejudicial and cause a mistrial or be grounds for appeal.
I do not believe this judge has no control over her courtroom - in fact, the opposite. What many see as a circus atmosphere is due to the defense attorneys acting in a squirrelly or sneaky way, and Juan is just not a prosecutor who makes a lot of objections or makes a big deal out of everything that he possibly could. Most prosecutors do not object a lot -- and most defense lawyers do not act as squirrelly as the ones in this case.
The judge's primary job in this case is to make sure that Jodi Arias gets a fair trial. Anything and everything else is secondary.