In the ruling, the PCC said that an original entry is what constitutes a blog post, not the comments posted in reaction to it plus the original entry.
Liddle, a former BBC journalist and controversial columnist, wrote in his Spectator blog that the "overwhelming majority" of various violent crimes were committed by young men from the African-Caribbean community.
A complaint was made to the newspaper industry's self-regulatory body the Press Complaints Commission (PCC) which found that Liddle's claim could not be backed up and failed to meet its Code's requirement of accuracy.
"It was difficult to argue that the sentence in question represented purely the columnist's opinion, which might be challenged. Instead, it was a statement of fact," said the ruling.
The Spectator said that Liddle was expressing an opinion, and even claimed that the PCC should consider not just the blog post but the comments made in relation to it, many of which disagreed with Liddle's statements.
"[The Spectator] said that blogging was a conversational medium in which readers were able to disagree with the writer's opinion immediately, as had happened in this case. In that sense, the piece as a whole had been written by the columnist and those who had commented," the PCC ruling said.
The PCC said that the Spectator had an editorial duty not to publish inaccuracies and that it could not rely on contributors disagreeing with the original piece to fulfil its duty for it. "The Commission believed that the onus was on the magazine to ensure that it was corrected authoritatively online.
It could not rely merely on the carrying of critical reaction to the piece," said the ruling.
The PCC regulates those publications which opt to be part of the regime and also regulates content on their websites which falls under the organisation's editorial control. This is the first ruling it has made on a publisher's blog posting.
"This is a significant ruling because it shows that the PCC expects the same standards in newspaper and magazine blogs that it would expect in comment pieces that appear in print editions," said PCC director Stephen Abell. "There is plenty of room for robust opinions, views and commentary but statements of fact must still be substantiated if and when they are disputed. And if substantiation isn't possible, there should be proper correction by the newspaper or magazine in question."