Is Dictatorship Unconstitutional?

Rachel Maddow has been doing a series of stories on the truly alarming authoritarian moves being made by GOPer governors and legislatures in a number of U.S. states.  They include laws to deny unions the right to organize, laws that create barriers to registering to vote, laws that substitute appointed dictators for local elected officials in municipalities deemed troubled,  as well as laws essentially voiding Roe v. Wade, imposing new and otherwise extra-legal conditions on whether a presidential candidate's name can appear on a state's ballot, etc.

While she has also emphasized the political response to these efforts, I kept waiting for the other shoe to drop: the courts.  Surely many of these efforts violate law.  Surely some of them are unconstitutional.  Surely the third branch of government is our ultimate protection.

But mostly that shoe has not dropped.  There is a challenge to Wisconsin's union-killing law, based however on violation of the state constitution not in terms of its content but in the process the legislature used to pass it.  Yesterday, Maddow reported a court challenge in Michigan to that state's Emergency Financial Manager law, and its use in overriding elected officials in the predominantly black city of Benton Harbor, and in the intended closing of a Detroit school that is a one-of-a-kind educator for pregnant women and new mothers who are predominantly black (and who almost always go on to college.)  This law empowers one state government-appointed person with essentially dictatorial powers.

The suit is citing Michigan law and one aspect of the U.S. Constitution, though only a section of the first amendment that allows the federal government to stop any state from violating legal contracts, such as those negotiated in collective bargaining.  

Which leaves me still wondering--where are the court cases?  Maybe they are still being developed.  Maybe people are reluctant to bring them.  It's acknowledged that women's groups aren't challenging state laws that restrict the right to choose because they fear that when those cases get to the Supreme Court, the current Court will rule against them and void Roe v. Wade entirely.  Could that be a fear in these other issues?

Or is it that the Constitution doesn't offer protections against such laws.  That states can constitutionally make demands on registration so that the right to vote is restricted,  as long as it doesn't involve a poll tax?  That states can essentially change the qualifications for federal office by restricting the ability to get votes for that office in that state? That states can allow child labor? That dictatorships are not unconstitutional, as long as it isn't at the federal level?  

I really would like an answer to these questions...