The Nottingham Review for August 1819 reports that a young woman charged with the murder of her bastard child, lately delivered, was discharged by proclamation. I guess this means she was seen as unfit to plead or had a statutory defence (post natal depression or similar) but I would like to be sure.
From the Shorter Oxford English Dictionary:
Proclamation: 1. The action of proclaiming; the official giving of public notice.
(Proclamations were usually made by the Government or by Courts.)
Discharge: [...] 4. To clear of a charge or accusation; to exculpate, acquit. 5. To dismiss (one charged with an offense); to release from custody, liberate. b. To send away, let go.
"Discharged by Proclamation" meant that the prisoner was released without trial or verdict (although they could be recalled later to face the charges again). This was typically because no evidence was presented against the accused, or no witnesses were able to testify against the accused. There is also at least one example, reading between the lines of a very convoluted debate in Parliament, when a judge discharged or tried to discharge a number of prisoners rather than travel an inconvenient 25 miles to try them -- see Hansard).
Another phrase you might come across in this context is "no true bill". (A bill, according to the Shorter OED, is a legal term for a written statement of a case; a pleading (esp. by a plaintiff); an indictment). If evidence was available, but a Grand Jury determined that it was insufficient to put the case before a judge and jury, they found 'no true bill' and endorsed the bill with the phrase Ign, short for Ignoramus (a Latin word whose legal use is to say 'we take no notice of it').
The National Archives has a catalog entry for a document of 1819 described as:
"Letter from Lord Sidmouth to the Clerk of the Crown for the County Palatine of Lancaster asking for returns of the prisoners, male and female, specifying dates of their commitments, their crimes, the verdicts and sentences, also of those who have been discharged either by Proclamation or because no bill was found against them."
To confuse matters slightly, the term 'discharged' was also used when the accused was found guilty but but the Court determined not to impose a penalty. "This usually signifies that while a crime may technically have been committed, the imposition of any punishment would, in the opinion of the judge or magistrates, be inappropriate." from Wikipedia. And it was used when a punishment was completed.
And to confuse matters even more, there are newspaper reports that refer to individuals being "acquitted and Discharged by Proclamation" (which probably means acquittal on one charge and not tried on another) as others clearly differentiate: "Six were sentenced to transportation for seven years; fifteen to be imprisoned, eight were acquitted, and four discharged by proclamation".
In the case in question here, it would appear likely that the individual concerned never went to trial for lack of evidence (or because the judge wanted to get home for his tea) but you would need to consult the court records to get the full story. The National Archives has Crown Minute Books for the relevant period/place, and Ancestry has "England & Wales, Criminal Registers, 1791-1892" based on the HO27 series of records at The National Archives (also searchable on the TNA site, but images aren't available there).
For more background on the legal system at this time, visit the Old Bailey Online. There are good explanations of the Legal System in England (and Wales) at that time, and the records there make interesting browsing, for example:
"John Addison, for Counterfeiting a Note to Receive Twenty Shillings of the Commissioners appointed to dispose of the Charity Money given for the Relief of the poor Protestants that were driven out of Ireland, was discharged without paying any Fine, or Fees, he being a very Poor, Sick and Lame, Creature, almost in comparison like unto a Skeleton."
"John Glass was discharged by Proclamation, for speaking Sedicious Words."
"Prisoner. I was going along with three more gentlemen, and this young man jumped out of the chaise and took me into a house to see if I had any knife about me, and I had no knife at all, that could cut the chaise; the sessions before last, I was discharged from it by proclamation for the same fact as I am now indicted for. Barton [A new witness] I was in the country and did not come home till the day after the sessions, and it was too late that sessions."
"Mr. Francis Smith and Mr. Sam. Harris having no Prosecutions entred against them, were discharged by Proclamation."