Yeah it's the overreach you have to worry about for each of the branches. The US currently has the problem of a lot of people resorting to the Supreme court to decide social issues, because frankly it's entirely too hard to organize it through the legislative. Despite the fact that drafting and responding to social issues, at least in terms of redefining laws anyway, is entirely a legislative power.
Like Roe vs. Wade is a contentious debate, but even putting aside how you feel about abortion, there is literally no way possible to interpret the base liberties defined in the constitution as in anyway defending abortion, baring the case where the mother's life is at risk either way obviously. It's for that reason, as well as the fact that the base question of how you feel about abortion depends on where you personally believe a baby counts as a human life that this remains a debate to this day where, unlike say Same Sex Marriage, opinions haven't moved basically at all since it was decided. Trying to redefine it as an issue of privacy was so utterly moronic that several legal dissertations on the thing have pretty much torn it to shreds, and even those supporting it think it went about the 'correct result' the 'wrong way', and it shouldn't have been a semantic wrangling of the 14th amendment's privacy clause at all.
Also, to show this is something that can go both ways in terms of the Left Right Dynamic and to avoid people who for some silly reason think Roe V Wade is an entirely sensible decision and not a wrangling of what was intended by the 14th amendment while giving them something more agreeable to chew on, a similar legal stretch can be found in the decision that basically determined that corporations can be defended by free speech to allow the creation of super pacs that basically came out of Citizen's United. While I think the effects of this are far less than what people think came from it (Hillary lost after all despite spending almost double Trump along with all the other massive advantages she had), there's a pretty massive distinction to be made between funding Political Activities and Political Speech. Organizations and Unions could talk up a candidate all they want, directly funding them however is a different matter entirely, even if it's with no actual coordination with the candidate, just funding massive campaigns is a separate matter frankly. Though granted I'm someone who prefers corporations and stuff to disassociate from politics at all where it doesn't directly affect them (In terms of a policy change in their industry or whatever, candidate support being a separate matter entirely from actual rule changes that could affect their bottom line and their employees), particularly when weighing in on contentious debates they have no place in.
To be clear, I agree with the Citizen's United Decision, as the case itself was directly referencing a movie against Hillary Clinton that was basically propaganda, much like Michael Moore's bullshit does similar stuff against say Bush and the like (He even did a Trump Movie before the election) and was similarly ruled in favor of when brought up to a court. That's fine because it's shit people have to actually want to go see and pay for themselves, so the only people who bother with it actually want to see it. Both of those are entirely fine, because I can choose to just not pay to support either and it's no skin off my nose. It's when it's directly adds that people can't really choose to not see that it's a problem, particularly when it sets skewed opinions in front of others that could affect election results, if not decide them as this election proved. My issue with the court case is that it defends those as well thanks to its redefinition of the First Amendment, and that's not something we want happening.
In a far less thorny debate, there's also the issue of the Executive's power to wage war that we've also been dealing with the US. The one with the real legal power to declare war is generally done through the Legislative and then approved by the Executive, but since Bush signed that one law that let him try to deal with the whole middle east situation (Another can of worms in itself), it's been stretched further and further since under both him and Obama to let them act in countries without having to get further approval from Congress. And now this same abuse of power has been placed in the lap of someone like Trump.
Suffice to say this is why making sure there are sufficient checks and balances is key and why overreach should be shot down wherever it starts to rear up. In terms of the US's core framework, baring the Judicial branch which in terms of the Supreme Court doesn't really have any checks in itself what we have is good provided it's used in the correct way. The Problem is with everything being so partisan it tends to lead to far more overreach unless we reach a gridlock situation. So really the government functions best when it can't do anything at all, it's when the powers align that people are screwed and the abuses start to pile up. Doubly so with a Judicial branch massively reinterpreting things to serve there own interest in increasingly vapid ways, that just leads to trouble no matter how you slice it.