[rockrr]

That's a new one for me and I'd love to see a reference to where Chase allegedly said this. Quite to the contrary davis was never not a US citizen and Chase believed that with passage of the 14th Amendment, a conviction would constitute a violation of double-jeopardy rules.

Chase made known to Davis' attorneys, a distinguished group of northern and southern litigators, his opinion that the third section of the 14th Amendment nullified the indictment against Davis. His contention was that by stripping the right to vote from high Confederate officials, a punishment for treasonable activities had been legislated, so Davis could not be punished again for the same crime.

http://jeffersondavis.rice.edu/FAQs.aspx

At any rate it was John C. Underwood not Chase who was hot to prosecute davis.

[BroJoeK]

rockrr: "At any rate it was John C. Underwood not Chase who was hot to prosecute davis."

The ultimate decision on all these matters lay in the hands of the President of the United States, Andrew Johnson.
Johnson removed the issue of treason trials in three key pardons:

1. In 1867, President Johnson "...issued a proclamation pardoning most Confederates, exempting those who held office under the Confederacy, or who had served in federal office before the war and had breached their oaths."

2. "Johnson sought nomination by the 1868 Democratic National Convention in New York in July 1868.
   He remained very popular among Southern whites, and boosted that popularity by issuing, just before the convention, a pardon ending the possibility of criminal proceedings against any Confederate not already indicted, meaning that only Davis and a few others still might face trial."

3. "On Christmas Day 1868, Johnson issued a final amnesty, this one covering everyone, including Davis.
   He also issued, in his final months in office, pardons for crimes, including one for Dr. Samuel Mudd, controversially convicted of involvement in the Lincoln assassination (he had set Booth's broken leg) and imprisoned in Fort Jefferson on Florida's Dry Tortugas."

Davis was indicted for treason while imprisoned; one of his attorneys was ex-Governor Thomas Pratt of Maryland.[139]
There was a great deal of discussion in 1865 about bringing treason trials, especially against Jefferson Davis, and there was no consensus in President Johnson's cabinet to do so.
There were no treason trials against anyone, as it was felt they would probably not succeed and would impede reconciliation."

Davis in prison:

Johnson -- Lincoln with Johnson campaign poster: