Slave owners had the opportunity and the right to take the case to the courts and say that the legislature and the executive weren't supporting their right to the return of their slaves with the appropriate legislation or action. If that failed they could take their case to the people in the elections.
But by 1864 everybody knew that slavery was on its way out. Nobody had much sympathy with the slaveowners' cause when the slavemasters were at war with the US. That wouldn't have been the case if 11 slave states weren't fighting the rest of the country, but they were. In any case, individual slaveowners still had the option of taking their case to the courts, right up until the time when slavery was abolished by the 13th Amendment.
x:
"Slave owners had the opportunity and the right to take the case to the courts and say that the legislature and the executive weren't supporting their right to the return of their slaves with the appropriate legislation or action." Right, and history gives us the example of 1842, Prigg vs. Pennsylvania where that did happen, but few others.
And I question if this problem wasn't overblown for political purposes, consider my post #791 above:
"More than 30,000 people were said to have escaped there via the [Underground Railroad] network during its 20-year peak period,[7] although U.S. Census figures account for only 6,000.[8]"
I'd first suggest the difference between one estimate of 30,000 fugitives over 20 years and the census figures of just 6,000 may represent the number of fugitives returned = 14,000 over 20 years = 700 per year ~60/month from five northern states =~maybe a dozen per month per state.
Which hardly seems like an economic, social or political tsunami.
And as I noted there:
"...from 1850 on, those were the responsibility of Federal officials to chase down & capture, not the states.
We also know that most, if not all, of those fugitive slaves escaped from Border States like Maryland or Kentucky, very few if any from the Deep South."
Of course, any Lost Causer worth his salt can tell you those Fugitive Slaves were the essential
Constitutional reason for secession -- they allegedly represented Northerners'
material breech of compact which dissolved Southern obligations to the Union.
But the reality of a few dozen runaway slaves per month from a population of
4 million, and virtually none of those escaped from the Deep South, seems to me under-whelming.