In This Guilty Land, Justice alone scores end-game VP for Support - each Justice marker scores one point. The more Compromise markers you can flip, the better. Using an Organization card to form a political party will flip half of the aligned Compromise markers to their Justice or Oppression side (depending on who is playing the card), and will exchange the other half with Compromise markers belonging to your opponent. On top of that, the acting player will score points equal to their Organizational Capacity. Together (action VP plus end-game) this can result in a huge swing, potentially transforming a losing position into a winning one.
But it can also be a double-edged sword. If a Justice player pins all their hopes on forming a party, expecting a huge last-minute reversal, they're going to find themselves losing matches where the card doesn't show up, and possibly winning matches where it does. There's a fair amount of swing factor in the game, yes, but if you pursue a "strategy" that depends on the luck of the draw, you're setting yourself up to fail more often than not.
And it's not like forming a party is fool-proof. Because the other half of those blue Compromise markers are going to turn red, Oppression will almost certainly take a huge lead in the House - a gap that will be hard if not impossible for Justice to close. And until the Senate changes at the end of the turn, Oppression will still be able to persuade Blue Compromise Senators, enabling them to pass Laws with impunity. It only takes a Fugitive Slaves Act card (or Any Law card used to pass a Fugitive Slaves Act) to suddenly flip many of those newly-acquired Justice markers to their Compromise side, reducing their end-game scoring by eight or twelve points. This is easier to recover from when you're forming a party in the mid-game - you have more time to claw your way back.
The best move for Justice is to plan for forming a party without depending on it. Make substantial gains naturally through Public Opinion actions, and balance cards from the Event Display and the Reserve. If when an Org card shows up you're only flipping one or two markers in each Region, your losses in the House won't nearly be as substantial; and if the Org card doesn't show up, well, you're probably in a decent position anyway.
Now someone stuck playing Oppression is probably wondering, well, what the heck am I supposed to do in all this? Well, for starters, I wouldn't suggest playing an Org card to form a party except for when it accelerates the pace of the game - remember, you score VP equal to your Org capacity when you take this particular action - simply because, just as is the case with Justice, doing so might give Justice the House and make it hard for you to recover.
The job of the Oppression player in these situations is to make it as hard as possible for Justice to pull off forming a party. There are only three cards in the deck that will potentially allow Justice to do this, and whenever one of those cards is used to up their Org capacity, it's removed from the deck. Passing Tariffs, especially early on, will force Justice to use either Org or Violence cards to compensate. Passing Fugitive Slaves Acts will flip Justice markers to their Compromise side, and can strongly disincentivize Justice from using a Violence card (lest they risk a marginalization defeat). Taking Public Opinion actions of your own that force Justice to React while their capacity to reflip used cards is diminished or non-existent (due to Tariffs) will also make them eager to use those Org cards to get themselves out of the hole.
What you're doing, in essence, is trying to create a situation where Justice must get the right card at the right time in order to save themselves - and then burning through the VPs as quickly as you can to end the game before they have that chance. (Bonus: the more VP you're racking up, of course, the less likely it is that the party move will save the day.)For both players, leverage and pressure is essential.