For the first decade of the PDGA, there was only one way to mark a lie, and that was by placing a mini in front of the thrown disc. Players eventually noted that while it got them a bit closer for putts, it was a bit of an imposition for fairway shots because there was an extra step where they had to bend down and place the mini. Dan Roddick (whose contributions to the sport cannot be underestimated) then introduced the idea of giving the player the option of using the thrown disc as the mark, removing the superfluous step of placing the mini. The result of that new marking option, which Dan did not realize at the time, is that for any given disc position, there are two possible lies. That anomaly has a number of undesirable consequences. The good news is that it can be easily fixed. The solution is to consider the thrown disc as the primary way to mark the lie, and to use a marker only when required to by the rules, or when the player wants to use the thrown disc. In that case, the marker is placed so that the tail edges align, and the lie does not change. Dan is a supporter of the proposed marking method and states that he would have added it back then had he thought of it.
Emphasize the use of the thrown disc as the marker. If a player wants to mark the disc on the ground (maybe to throw it), they mark it by aligning the tail edges of the disc and the marker. That way, the lie is the same lie they would have had by using the thrown disc as the marker.
To me, that is patently obvious. A player throws a drive that lands in the middle of the fairway. How many possible lies should there be? The answer is clearly one: the lie that is determined by the position of the disc. The player may or may not want to use the thrown disc for their next shot. If they choose to use it, the lie should be the same as if they had chosen to leave it on the ground and use a different disc.
The primary motivation to mark with a mini - other than habit - is to get eight or so inches closer to the target. With tail marking, that slight advantage is no longer in play, as the player no longer gains distance toward the target by marking with a mini. Except for cases where they want to use the thrown disc, they will just use the thrown disc as the mark. That eliminates the process of getting the mini out, placing it in front of the thrown disc, and then picking up the mini after they have thrown. That process, repeated dozens of times over the course of a round, takes a nontrivial amount of time. If players are no longer motivated to mark with a mini, play will flow better and rounds will go a bit faster.
Since it is larger, a thrown disc is easier to see when looking for stance violations on throws that have a run-up.
Imagine a drive that straddles the 10m line. Is the player putting? We don't know until the player marks. If they use the thrown disc, the lie is outside the 10m circle and the player is not putting. If they mark with a mini, the lie is within the 10m circle and they are putting. We now have a single disc position which results in the application of two different sets of rules depending on the marking method chosen.
The following happened in my group in a tournament recently: In the last round, two players in my group were competing for the last cash spot. Near the end of the round, each of them had a downhill 18' putt with OB past the hole. They asked me to determine who was out, each one hoping the other would putt first. I stood between their lies, pausing because it was very hard to tell. Player A then marked his lie with a mini and asked, smiling, "Now who's out?". Because his lie had now moved forward about 8 inches, I replied that Player B was now out. Of course Player B caught on, and marked his lie with a mini to move it forward as well. I hope it's clear how ridiculous this is.
Imagine the following exchange between announcers for the Masters in Augusta:
"It looks like Jordan Spieth has a tricky putt." "Is he putting from the fringe, Bob?" "We won't know until he marks his ball. He might mark in front or behind it." "He gets to choose? I thought the ball could only be in one place." "It's a crazy world, Dave."
As the recipient of rules questions from the PDGA website, I get this question several times a year. While it hasn't been formalized as part of the doubles rules, my response has been that they should play from the same lie.
I've been playing this way - only marking with a mini when necessary (OB, lie above ground, etc) - for more than five years, and I enjoy the way play flows. I carry two identical putters to clean up missed putts, so that I don't need to use the thrown disc. Many prominent players (for example, Paul McBeth) prefer to use the thrown disc as the mark. Many disc golfing friends of mine with whom I shared the idea starting in 2011 have come to prefer playing this way as well.
Imagine that we were just now getting around to formally codifying the rules of disc golf, and we've already decided that we like being able to use the disc on the ground as the mark, though we recognize that there are situations where that is either impossible (OB, disc above ground) or undesirable (player wants to throw that disc). We decide that you can either use the disc on the ground, or a mini. After some analysis, we see that there are two different ways to mark the lie with a mini, either at the nose of the disc, or at the tail. One way results in a different lie than the disc on the ground; the other results in the same exact lie. Which way would we choose?
That in itself is not an argument. It argues against change of any sort until it provides details. Until then, it is simply a statement of preference. There is a clear and reasonable argument that our current marking method is broken, as detailed above.
That is another argument against change in general. Do we really believe that players will be intellectually incapable of figuring out a new marking method? The introduction of the thrown disc marking option long ago did not result in confusion. Every player I have explained it to has grasped it immediately.
That is highly speculative. A majority of players I have presented it to understand the logic behind it and feel it's an improvement. When presented with changes, almost all players simply adjust and move on. The current marking method is player-friendly, as it allows players to gain eight or so inches on the target. That in itself doesn't make it a good rule, though it's something to take into consideration. As a thought exercise, imagine that you were allowed to play from within five meters of your thrown disc in any direction. That would be very popular among players, but it wouldn't be a good rule. Or imagine if you were allowed two mulligans per round. Same thing.
While that may be true, there are plenty of opportunities for strategic choices elsewhere. It also begs the question that if having two possible lies is good, would more be better? We could allow marking anywhere around the circumference of the thrown disc, or within a certain distance from the thrown disc.
I consider that a marginal argument at best. Such lies are rare, and are already possible with rollers. With the new lie area, you may be able to play to the side. Worst case, you play from behind the tree (possibly directly behind it if it is less than 30cm in diameter).
I've long suspected that Big Mini might be secretly lobbying against tail marking.
I encourage anyone who's interested to try it out during practice rounds. The inevitable result is that you stop marking with a mini since there's nothing to be gained. The only cases where you would mark with a mini are if you're OB, above ground, or you want to use the thrown disc. For that reason I carry two identical putters. I've been playing as if tail marking were the rule since 2011, and I find that rounds flow better without the additional step of marking each lie with a mini.
It was the opinion of the Rules Committee in 2013 and it remains our opinion now that the arguments for tail marking far outweigh the counterarguments. The first two arguments are enough to recommend the change. The counterarguments boil down to "I'm used to the current way, let's not change anything". I've yet to see a cogent argument in favor of nose marking on its own merits. It's important to realize that disc golf remains a relatively young sport, and we should not hesitate to get things right when we have the chance. This is one of those chances.
Conrad Damon #2450, Rules Committee chair