Player's equipment; uniform, cleats, shin guards. What's so confusing about that? The devil is in the details and the other things people like to wear. The five principal problems that arise from not understanding Law 4 are footwear, jewelry, mismatched uniforms, medical equipment and the Referee. 

Referee
We'll begin with the last item first. The Referee is not equipment but the Referee is the final say in whether any piece of equipment is allowed.  Law 4 and Law 5 (the Referee) merge on the issue of player safety which is the key factor in all of the Referee's decisions regarding the match. What follows is a guide to the minimum standards of Law 4. All involved must always remember that the Referee is empowered by Law 4 and Law 5 to exclude any piece of equipment or attire that he or she deems unsafe to a player or opponent. Even if that decision seems to contradict any of the following. The Referee’s decisions regarding a match are final and cannot be overruled by a parent, coach or league official.

Shoes
Flip flops are not allowed because the open toe is a hazard to the player. Work boots are not allowed because they pose a danger to an opponent. Pretty simple concepts that again revolve around safety.

Sneakers are often allowed. There is nothing that says a shoe must have cleats, it’s just a good idea to use them. If a match is played in wet conditions, sneakers may be deemed as unsafe by the Referee and not allowed although we are not aware of any circumstance of this happening. Soccer cleats are best.  Baseball, football and other field sport shoes often have a cleat under the toe which is considered dangerous and will almost certainly not be allowed by the Referee. Shoes that are torn or in bad repair may also be deemed as unsafe for competition.

Jewelry
Can’t wear it in a match. This includes all piercings and rings. FIFA/USSF/NHSA are all unequivocal on this point. It poses risk of injury to both the wearer and the other players on the pitch. Law 4 is clear on this matter which has been reinforced by the State Referee Committee (SRC). All referees have been instructed by these organizations to look for jewelry and keep it off the field. They have no choice in the matter. Taping does not make jewelry safe. A doctor’s note does not suspend Law 4. Don’t make the ref the bad guy for following Law 4.

Two years ago, one area league made a change to the Local Rules of Competition (more on that the LRC in the future) to allow for taping of recent piercings for their young players so that holes didn’t close up. The SRC wouldn’t provide referees for matches until the rule was abandoned. USSF backs up this position. 

There is an exception which may allow players to wear jewelry. Medical Alert jewelry is allowed provided it is properly taped down (the only case where this is permitted) and does not pose any danger to the wearer or other participants. The referee still has the final say as to whether it is safe or not to allow the player to play.

Mismatched Uniforms
Maybe it is or isn’t a safety issue but Law 4 is clear that uniforms (also called kits) are to be, well, uniform. This means that the socks, shorts and tops match for all the players on a team. Mismatched uniforms make the ref’s job unnecessarily hard. It is well within the Referee’s prerogative to not keep a player off the field because the color of the shorts or socks are wrong. Shorts that are too large or small can be exchanged with the equipment manager. We have lots of extra shorts.

Medical Equipment
It is largely recognized that soft braces and soft casts are permissible. Hard casts may be allowed if deemed safe by the Referee. You can improve the likelihood of a hard cast being allowed by covering all surfaces with high-density, closed-cell polyurethane at least a ½ inch thick or an alternative similar padding. Be aware that even if the it is covered, it’s still the Referee’s decision as to whether the cast is safe to others. A player may still be not allowed even with a covered hard cast.

Mouth guards not required under the Laws of the Game, however MSJSL as well as many other area youth soccer organization strongly recommend the use of them. Mouth guards are cheaper than dental work.