Kai Koon Ng
One of the unwritten responsibilities of a Head Judge is to maintain the integrity of the event. A natural extension of this is to maintain the integrity of your staff, which is largely made up of your judges. It is important to remember that your judges are human; they will make mistakes. Most of them will have their own lives outside of Magic, and while most will make the utmost attempt to keep current of the latest rulings, some are likely to slip through the cracks. Some don't even make the effort, and will likely be more of a nuisance at the event than any help, since every other ruling they make is wrong.
When the Head Judge is called to a table, there is usually some dispute as to the rulings. My practice has always been to have the judge at the table explain the situation and his rulings, before I talk to the players. By asking the judge to explain the situation, it projects the image that you trust your people. If you go to the players directly, it tends to imply that you have doubts about the judge.
Often, you will find that there has just been a misinterpretation of the situation by the judge in question, and once that is cleared up, the judge is perfectly capable of making the appropriate ruling. In these cases, let the judge make the ruling, and if the players have any argument, step in, and make sure they know that you, as the head judge, support that ruling.
Now, if the ruling made by the judge is wrong, then you will have to step in and make the appropriate ruling. Explain the ruling to the players, and then take the judge aside and go through the ruling with him. It is always preferable to do this in private. Whatever it is, do not give the players the impression that you are scolding the judge, or telling him off. If you really need to tell him off, pull him aside to some corner where you cannot be seen. Basically, arguments such as these should be kept completely private.
Judges who insist on arguing your decision should be subtly led aside where the discussion can be continued away from the eyes of the players. Keep in mind that such arguments are actually very disruptive in two ways. Firstly, they tend to undermine the authority of the judges. Secondly, it is distracting to the players at the table you are at will sort of freeze until a decision is made. In addition, the players at the next few tables will also look over to see what the commotion is. While it is important for ALL judges to know that he should not be arguing with the head judge, it is also the head judge's responsibility to ensure that arguments are to be done in private.
In rare cases, you are going to get a judge who is really incompetent in rulings. Due to the recent upheaval in the rules due to 6th Edition, many of the judge's understanding of the rules are out of whack. Basically, unless he is being completely disruptive to the event, redeploy him elsewhere, where his lack of rules understanding will not be a hindrance. The best examples are deck checks, and data entry. Try to be diplomatic, and give the impression that you are just cycling staff around. At the end of the day, take him aside, and let him know about his rules deficiency. Again, it is important to be diplomatic. Until high pay for judges are introduced, most judges are volunteers. If you ever hope to get him to help you out in a tournament again, don't shout and scream at him. Let him know that perhaps he needs to brush up on his rulings.
The last instance where there could be conflict between the judge and senior judge is in terms of penalties. This is quite a sensitive area as different judges have different interpretations of the penalty guidelines. This is most evident in the cases of 'deliberate'. There is really no hard and fast rule on what is deliberate. Sometimes a judge might feel strongly enough about his case that he starts arguing for it. Again, this does not present a good image about the judging staff to the players.
The way I get around this problem is that with judges that I have never worked with or are inexperienced (Level 1s and trainees), I will have them check with me before issuing anything more severe than a single warning (ie anything involving game loss, duel loss, ejection, and disqualification). That way, if he has concerns about the penalty, it can be discussed in private. With those whom I have more working experience with, I will tend to give them more latitude. How much latitude will depend on the judge's experience, as well as his rules savvy. However, as stated in the floor rules, anything that involves ejection or disqualification will have to come from the head judge.
The disadvantage of this system is that it does give your judges (especially those whom you have hardly worked before) an impression that you do not trust them. Thus, it is important to let them know the reason this is being done. Generally, when they see that I apply the same rule to my regular judging staff as well, they are less hostile to the idea.
In conclusion, it is important that the head judge knows that not only does he need to treat his players with respect, he needs to treat his judges with respect as well. Conflicts between the head judge and the judges are bound to occur, and I always felt that you will get better results having them work with you rather than work for you.