By Maggie Shiels
Technology reporter, BBC News, Silicon Valley
The hearing was seen as a major milestone for both sides
Google's efforts to create the world's largest digital library remain in limbo after a US judge declined to rule on the case immediately.
Ahead of a day of arguments from supporters and opponents to the books project, Judge Denny Chin said he would issue a written decision.
Critics said Google's deal with US publishers and authors would give them a monopoly over online book sales.
Google said it would make "millions of books searchable via the web".
To date Judge Chin has read more than 500 submissions related to the $125m (£77m) settlement that would set up a book rights registry to pay authors and publishers compensation in return for their work being scanned and digitised.
For five years Google has been trying to finalise this agreement and for months both sides have been rehearsing their arguments in public.
The "fairness" hearing in front of Judge Chin was seen as an important milestone following a protracted series of postponements.
But at the start of proceedings in New York, Judge Chin said "to end the suspense, I'm not going to rule today. There is just too much to digest. I have an open mind."
The hearing was seen as a showdown that has long been in the making.
In 2004 when Google's scanning of books brought it into conflict with the Authors Guild of America and the Association of American Publishers, and they sued over "massive copyright infringement".
By 2005 a deal was hatched that needed court approval and drew the ire of a myriad band of critics. It was amended at the end of last year.
In the end 21 parties opposing the agreement made their case in the five minutes that was allotted to them. Those against the settlement outnumbered its backers three to one.
Google's digital library plans have been controversial from the start
Technology giants like Sony and Microsoft were pitted against one another.
Sony, which makes electronic book readers, supported the deal because it was good for competition. Microsoft's Tom Rubin disagreed and said it "was structured to solidify Google's dominance".
Amazon's lawyer David Mimmer told the judge the agreement allowed "full scale commercial exploitation with essentially no restraint whatsoever. It turns copyright law on its head".
The Department of Justice (DoJ) also spoke out on anti-competitive grounds and said Google's attempts to amend the deal meant "substantial issues remain".
However the DoJ also said an approvable settlement could be worked out that might require rights holder to opt in to the deal.
Foreign governments made their voices heard too.
France and Germany said they backed a European book-scanning project called Europeana which asks for permission from copyright holders before books are scanned and digitised.
Google has scanned around 12 million books to date
Other opponents were worried about privacy and Google's ability to track users' reading habits and collect data on them.
After the hearing Google said "we appreciate the concerns voiced, but we believe this settlement strikes the right balance and should not be destroyed to satisfy the particular interests of the objectors."
Lawyers estimate that it will be some weeks before Judge Chin delivers his verdict.
"This is just another chapter in this story," Cindy Cohn, legal director of the Electronic Frontier Foundation told BBC News.
"If the judge greenlights this without privacy restrictions, we would have to consider where we stand as regards an appeal. Whichever way he rules, I think we can be fairly sure there will be an appeal by somebody."