It depends on the area of law but there's generally a balancing test as to whether or not a court should issue an injunction. There are a number of factors such

It depends on the area of law but there's generally a balancing test as to whether or not a court should issue an injunction. There are a number of factors such as the likelihood that the plaintiff will succeed but also if the injunction (or lack thereof) causes permanent harm or can be reversed. Imagine a court was considering the issue from years ago when Australian authorities were deciding to release the cane toad to kill sugar cane pests. That's not a decision taht you can take back. Once they're released, there's really no rolling that back. So a court would generally side on issuing an injunction pending an appeal for that very reason. As a historical side note, the cane toad was released and it's been an ecological disaster ever since. Now imagine another case where a government agency is requiring all fishing boats to install transponders and they're relatively cheap. There's reallly no irreversible harm either way so a court will tend to look instead at the likelihood of the plaintiff prevailing instead. At least that's how it should work. In practice, particularly with the Supreme Court through its entire history, there's a fairly accurate way of predicting how they'll rule: pick the side that favors the wealthy and powerful and that's how they'll rule way more often than not. There are exceptions to this and it's not universal (eg decisions rolling back segregation) but it is (IMHO) arguably the best predictor.