Trump-Ukraine scandal lights up Washington. Cue oversight debate.

President Donald Trump’s apparent pressure on the leader of Ukraine to investigate former Vice President Joe Biden and his son is only the latest norm-busting behavior from a United States chief executive who has long reveled in pushing past barriers that constrained his predecessors.

From revoking California’s ability to limit auto pollution, to attempting to add a citizenship question to the Census, to declaring a national emergency to build his border wall, President Trump has tried in numerous ways to take contentious actions he wants, sometimes against the advice of his own Cabinet members.

The legality of many of these actions remains to be seen. Lawsuits may