The jury is still out
Judgement has not yet been finalised on a particular subject; especially due to information being incomplete.
'The Jury Is Still Out' has been a staple headline in US newspapers for at least 150 years; for example, this from The New York Daily-Times, May 1850:
"The [Gardiner Trial] Jury are still out, with no prospect of immediate agreement."
The phrase has continued to be used in this literal sense. The emergence of the figurative use of 'the jury is still out', i.e. as a reference to a non-legal decision where no actual jury is involved, began in the USA in the 1940s and has now become somewhat hackneyed; for example, the expression was used in a report of a baseball game, published in the Indiana newspaper The Terre Haute Star in July 1949:
The jury is still out on his [Orestes (Minnie) Minoso's] batting ability.
There are a few examples of the phrase's use, mostly in a sporting context, throughout the 1940s and 50s, but it was a specific event that brought it fully into the language - the infamous Finch-Tregoff murder trials in 1959/61. Dr. Bernard Finch was a middle-aged Los Angeles surgeon and Carole Tregoff was described in newspapers at the time as 'his shapely young receptionist'. The murder of Finch's wife and the subsequent trials were a cause célèbre. At each of the the couple's three trials the jury took their time in coming to a judgement and hacks must have got tired of typing 'Jury Still Out' each day. This newspaper cutting was typical of the hundreds of stories that ran during 1959 to 1961:
At the third trial, during March and April 1961, the pair were finally convicted of murder.
Had Dr. Finch kept his mind on surgery, we would probably not now have the cliché 'the jury is still out' at our disposal. I'll leave it to you to decide whether that's to the good or not.
See other phrases that were coined in the USA.