Can Washington effectively govern any longer? Bitter partisanship has become such a feature of American politics that voters have understandably lowered their expectations about the effectiveness of our institutions.

Now that partisanship, and a growing trend toward maximalist politics, has escalated the tension between the legislative and executive branches to a level that threatens a complete breakdown in governance. A blizzard of investigations by the Democratic House into the executive branch and into the personal finances of the president and his family has resulted, predictably, in an all-out strategy of blocking those efforts. As the subpoenas and lawsuits pile up between both ends of Pennsylvania Avenue, the courts face a legal tangle that threatens to lead to utter futility when voters split power in Washington.

The subpoenas issued by Congress as part of over 20 separate House probes of Trump, his family, and his administration pertain to a mix of private finances and official government operations. The administration and its defenders call this an unprecedented example of harassment, and note that it comes after a special counsel resolved a two-year probe into the 2016 election without developing evidence of criminal conduct by Trump and his campaign. Still, some of these oversight efforts are reasonable and focused on government operation, even if they are arguably being conducted unreasonably.

At issue is whether we have co-equal branches of government and to whom each is accountable. Democrats in Congress have issued subpoenas arguing that their authority to conduct investigations into the executive branch and the president is absolute. However, nothing in the Constitution explicitly grants one branch that kind of unlimited authority over another. Article I Section 6 prohibits the executive branch from arresting legislators while Congress is in session, a clause which has been generally interpreted as limiting executive branch investigations into members of Congress. For instance, an FBI raid on former Rep. William Jefferson’s offices in a corruption probe brought an immediate and bipartisan challenge from congressional leadership, and the FBI returned documents seized in the raid. (Jefferson later got convicted and sentenced to 13 years in prison, and served over five years.)

That limitation should suggest a similar and reflexive limitation on Congress’ ability to investigate the co-equal executive branch. And indeed, the courts have found such a limitation. The Supreme Court ruled in Watkins vs US in 1957 that Congress’ authority to investigate is tied to its legislative interests. The context for that decision dealt with private activity, not government operations, in which Congress has a clear and significant standing interest. The mix of investigations might make it difficult for the courts to deal with the conflict between the White House and Congress in a consistent manner that addresses the independence of each.

Nevertheless, at some point the Supreme Court will have to find a way to apply a limiting principle to congressional authority in regard to the executive branch, through Watkins or on its own. The alternative, where Congress has investigative authority without limit, promises an outcome where no executive from a competing party can possibly govern. We will have backed into a proxy parliamentary system, where the executive serves at the whim of one or both chambers of Congress.

We have already seen how that will come to pass. Committees under the control of the other party will issue subpoenas at will, enforcing those subpoenas through ruinous fines or detention through “inherent contempt” powers. There will be no dividing lines between private behavior and public action, and even normal exercise of the latter will result in endless demands for hearings and threats of self-enforced contempt actions. Even if this present session of Congress declines to go quite that far, the escalation and precedent set now will get amplified and expanded in a tit-for-tat fashion as has already been seen in the Senate’s confirmation processes for the past two decades.

Eventually, parties will simply refuse to allow any opposition White House to function. Presidents will struggle to find qualified appointees to fill roles within an administration regardless of whether those positions require Senate confirmation or not, if appointment means continuous character assassination. Even when those roles do get filled, the disincentives for action will mount to the point of paralysis -- unless the party controlling the White House also controls both chambers of Congress. At that point, any exercise of oversight will have become so toxic that political parties will refuse to apply it to their own executives.

Many Western democracies use parliamentary systems to generate their executive functions, a structure that leaves the executive entirely accountable to the parliament. The American system, however, elects Congress and the president separately. The president derives his or her authority directly from the states and the voters, not Congress, and that is where political accountability should lie as well. The attempts by the House to overwhelm this administration with subpoenas and contempt actions is an attempt to usurp the authority of both the states and voters, and to impose a parliamentary system by proxy. It will set precedents that both parties will exploit for revenge, and both parties will live to regret.

Unfortunately for the courts, this situation is so unprecedented that an easy solution will likely prove elusive. Let's hope the courts apply Watkins broadly enough to require Congress to either take the politically risky step of impeachment proceedings to deal with actual high crimes and misdemeanors, or stick to oversight functions that relate directly to their legislative authority. Anything less will eventually upend the principle of co-equal powers and undermine the constitutional order of the last 230 years.