They can be measured by the increase in party-line voting in Congress, the bitter political atmosphere in Washington, the political segmentation of media outlets and the emergence of rigid donor and activist bases in each party that use their power to inflict Stalinist party-line orthodoxy on potentially independent leaders.
On 10 May 1976, amid rising criticism, he resigned as Liberal leader, again categorically denying Scott's allegations but acknowledging the damage that they were inflicting on the party.
A coroner's jury closed the case after a few days, ruling that Sparkman had died from wounds inflicted by parties unknown.
But the much bigger issue is the long-term damage that Trump is inflicting on his adopted party.
He said: "It is the most extraordinary self-inflicted wound I have seen an opposition party inflict on themselves in many, many years".
In an open letter to Corbyn, former shadow minister Jamie Reed urged him to act to "repair the damage inflicted to the party" in recent weeks by a series of damaging, self-inflicted stories.
Cameron spoke after his party inflicted a humiliating byelection defeat on the prime minister.
But is Hutchison's candidacy, and the angst it inflicts on the party, "best for Texas"?
Later that day the party inflicted a symbolic Commons defeat on the government with the passing of an opposition day motion calling for a pause in the rollout.
But Mr. McConnell is also warning Mr. Trump of the damage it could inflict on the party heading into the 2020 elections.
This is the Blair Catch 22". They also give a withering picture of the damage inflicted on the party by Mr Blair's decisions on Iraq.
