When the thrower is positioned near the sideline, the marker "forces line" or "traps line" by positioning his or her body directly between the thrower and the middle of the field. The idea, of course, is to greatly restrict the area in which a receiver can cut for a non-break-mark throw. The defenders then attempt to play so that the receivers cannot get open in this restricted area. But the offense still has plenty of options and there is no need to panic when faced with a trap. Indeed my team usually expects to exploit the trap to our own offensive advantage.

From the offense’s perspective, the first thing to realize is that the area in which a cut can be made is not as small as it seems. There are two wedges of space (numbered 1 and 5 on the diagram) in which the marker makes no attempt to challenge the throw, and two other wedges (2 and 4) that require only a relatively easy break-mark pass. Only the area directly behind the marker (wedge 3) requires a difficult throw if the marker is playing correctly, and even there a relatively poor hammer or scoober can work if the receiver is open enough. Wedge 1 is the most desirable place to complete a pass, since it allows the biggest yardage gain and since the marker cannot challenge a throw to that area. But if the thrower thinks "I must complete a throw into wedge 1", or if the receiver thinks "I must get open in wedge 1", then the offense is already playing into the defense’s hands.

To help think about various offensive and defensive options, let’s consider a standard play when faced with a sideline trap. For simplicity assume that the disc is being put into play at the line, but the same principles apply if the disc has just been caught near the line. The stack sets up well off the line, usually at an angle away from the thrower, and the second or third person from the front cuts deep at an angle to the sideline, into wedge 1 (see diagram). If the defender stays close, then the receiver cuts back hard towards the disc (known as a "comeback cut") for an easy 20- to 40-yard gain; if the defender stays back anticipating the cutback, the receiver continues down the line for a longer pass (the "away cut"). Either of these throws should be fairly routine for a decent thrower, though the longer throw is harder. Given a good throw and an alert receiver, this play is very hard for the single defender to stop.

Fortunately for the defense, they need not rely on just person-on-person coverage downfield. The defense has two simple resources to stymie the standard cut: send a defensive player (often the one covering player 6 in the diagram) towards the line to cut off the deep throw, or poach a player from near the disc into wedge 1 to shut off the shorter throw. Providing help on the deep cut is the more usual of these two options---the deepest defensive player moves well over towards the line. If the stack is set up correctly, doing this will require leaving the deepest offensive player (number 6) open by many yards, and unless the defense reacts this player can often cut toward the disc, into wedge 1, for an easy big gain. The defense needs to switch someone onto this player---either another defender from the stack, or the defender who was covering the original outgoing cut. Using a defender from the stack may leave that defender’s player open for an easy break-mark throw in wedge 2 (or for a wide-open hammer in wedge 3), so it’s usually better to use the defensive player who is already in wedge 1. Making this switch requires good timing on the part of the defensive players involved---too early, and the original receiver can cut back down the line, but too late and the number 6 receiver will run right past the defender before the defender has had a chance to change direction.

Beyond this point, there are so many options for offensive cuts and defensive responses that it would be confusing to enumerate them all. But the basic principles are fairly simple: the offense tries to get someone open in wedge 1, and the defense tries to prevent anyone from getting open there, while not leaving themselves too vulnerable to break-mark throws.

OK, so suppose you’re the thrower. The stall count is on five, and nobody has gotten open in wedge 1. What should you do? First, realize that your immediate goal has changed: you are no longer trying to exploit the defense for a big gain, you are now just trying to complete a pass. There are two other prime areas, besides wedge 1, in which to complete a pass: wedge 2 (a relatively easy break-mark throw) and wedge 5 (a dump pass). In order to make both of these areas viable options, you must face the marker. This may seem a bit odd at first, since there’s a tendency to fixate on the eventual goal---the end zone---and to forget about your short-term goal of just making a completion. But when you’re facing downfield, you have no way of throwing into wedges 3, 4, or 5. That makes the marker’s job easier, and it also makes the other defenders’ jobs easier since they know that they don’t need to worry about covering the dump pass, the cross-field hammer, and so on. So when it’s obvious that you won’t have a receiver in wedge 1, or on stall 5, whichever comes first, you should face the marker. You can always pivot back, if someone gets open in wedge 1. (By the way, if it’s very windy or if you aren’t confident in your throws, consider facing the marker right away rather than looking for a wedge 1 cut first.)

Once you’re facing the marker, your easiest throw will probably be one of the following:

1. Receiver #1 fakes a cut for the dump pass, then runs up the line into wedge 1.
2. Receiver #1 cuts for the dump (wedge 4 or 5).
3. One of the downfield receivers (#3, or one of the players who has already cut into wedge 1) fakes a wedge 1 cut and then cuts into wedge 2 for a break-mark throw.
4. One of the receivers in the stack is left open by a defensive poach, and cuts into wedge 3 for a cross-field hammer or other hard-to-prevent throw.

Either of the first two of these throws lets the defense maintain the trap...but that’s OK, the offense can just set up the same way and try again. Options 3 or 4 move the disc well off the line, thus breaking the line trap. More important, they move the disc across the field so that all of the defenders are now out of position. Once the disc moves off the line, the offense should try to hit several consecutive throws down the other side of the field. Some offensive players have the habit of looking back towards the part of the field the disc came from as soon as they catch a pass---that’s a bad habit in this circumstance. First look towards the other sideline, and try to complete a pass there.

If the disc does stay near the line the defense should usually try to maintain the trap, since the downfield defenders are already positioned for it. One thing to watch out for is for the offense to chain together several consecutive throws down the line, once the first one is complete. This sometimes happens when the deep defender gets pulled in to cover someone (perhaps even the new thrower), so there is no longer anyone available who can provide deep help. In this situation an offensive player cutting up the line can usually get open for the comeback cut, since the defender has to pursue hard on the away cut. This receiver can make the catch, turn, and look for another teammate making the same cut. The defense can prevent this in several ways: by taking away the throw down the line for a couple of seconds (that is, by forcing middle); by having one of the defenders poach into the passing lane to shut down the throw to the comeback cut for a second or two; or by anticipating the comeback cut and daring the thrower to make the deep throw. Each of these creates an obvious opportunity for the offense, so it’s important for all of the defenders to see what’s going on and to work hard to minimize the weaknesses.

When my team applies a line trap, we expect to generate a turnover, or at the least force up a low percentage throw. When we face a trap, we expect to get a big gain. If you apply these principles, you can make the line trap work for your team, too.

1. Play defense on the dump receiver! If you want to poach into the lane, do so only at a low stall count. If the offense throws a dump pass, you must get there in time to stop them from keeping the disc moving towards the opposite sideline.
2. Help your teammates. If you’re the deepest defender, you may need to help prevent a long pass. If you’re covering someone in the stack, you may need to help if someone is open and is cutting into wedge 1.
3. If your player cuts towards the disc or towards the line, move so as to keep your body between the receiver and the disc, and between the receiver and the line. Don’t play "turnstile D", where the receiver runs past you as you turn around and try to follow.
4. Look at the whole situation on the field, and anticipate what the offense will do: if the person you’re covering starts a deep cut in wedge 1, and if you have deep help, then expect the cutback; if a pass is thrown to a receiver well off the line, expect the offense to try to swing the disc to the other side of the field and position yourself accordingly.
5. If the receiver gets a step on you back towards the disc, don’t let up...go harder! Make the receiver sprint straight at the thrower---it decreases the margin of error for the thrower, makes the relative speed higher and thus makes it a harder catch, and may give you an opportunity for the block if the receiver slows down.
6. Prevent a direct throw into wedge 3, if you’re the marker. The whole point of the mark is to make that throw difficult, since a completion into wedge 3 often gives the offense the opportunity to string together several more throws down the other side of the field. If you can’t prevent the throw, at least make it a difficult throw or a slow throw like a hammer.

1. Never crowd the sideline. If your defender moves over towards the sideline, don’t follow unless you can actually cut into the wedge and get open.
2. Punish the poach, whether you’re a thrower or a receiver. If you’re the thrower and you can’t hit the open player, just try to throw a quick completion (a dump pass is fine)---the new thrower can often hit the open player in the second or two before the mark gets set.
3. React to the situation on the field. For example, if one of your teammates calls "poach", try to cut so as to leave a lane for the thrower to hit that player. Don’t let your defender shut down both of you!
4. If you receive a break-mark pass, try to complete another pass in the break-mark direction.
5. Call "poach" if your defender leaves you, to tell the thrower and your teammates that you are unguarded, and immediately run to an area where the thrower can hit you. If there is no such area, then run for the end zone---even if the current thrower can’t get the disc to you, you’ll be open for the next pass or the one after. And at least your defender will have to worry about you, and won’t be able to devote full attention to his or her nefarious plans.
6. Emphasize completions, not yardage. Above stall 5, the goal is no longer to gain big yardage, it’s just to complete a pass. Face the marker and throw a completion, even if it’s a dump pass or if it lets the defense maintain the trap.