For example, in the US, the Supreme Court is often seen as the arbiter of constitutionality. If the legislature or the executive can get the Supreme Court, then, to give its approval to a limited, innocuous-seeming version of an abuse, it can then point to that as a seal of legitimacy — and the tactic frequently succeeds, mollifying what would otherwise become public outrage.
An example is the Supreme Court resistance to, and final acceptance of, FDR's New Deal policies. When the court finally relented and allowed Roosevelt to proceed, it took the wind out of the opposition, which might otherwise have put a stop to it. Instead, similar policies have proceeded without opposition ever since, and finally gained acceptance by both sides of the political establishment.
In the end, the only check on abusive government is the people, which must be able to identify tyranny and have a will to oppose it by either voting the bums out, resisting their abuses directly, or forcing them out if necessary.