Deputy Labour Leader Harriet Harman called Lord McAlpine's legal action against Twitter users who wrongly linked him to child abuse claims "a wake up call".
The Shadow Culture Secretary told ITV1's The Agenda With Tom Bradby, "It's a reminder that it's [Twitter's] not a no-go zone for the criminal law or the civil law".
"I think Twitter helps with the news. You find out things so much more quickly - that is unless you're the Director General of the BBC," she added.
The Agenda will be broadcast at 10.35pm tonight on ITV1.
More top news
A primary school has taken action after pupils brought in an variety of "worrying" packed lunches - including a two-day-old McDonalds.
A 30-year-old man was arrested in Birmingham on Sunday on suspicion of preparing terrorist acts.
Two students and their climbing instructor are feared dead after an avalanche hit a school party in Japan.