Wiktionary
n. (context pejorative English) A state whose government institutions are authoritative and over-paternalistic, interfering with and controlling people's lives. (from the mid-20th c.)
Wikipedia
Nanny state is a term of British origin that conveys a view that a government or its policies are overprotective or interfering unduly with personal choice. The term "nanny state" likens government to the role that a nanny has in child rearing. An early usage of the term comes from Conservative British MP Iain Macleod who referred to "what I like to call the nanny state" in the December 3, 1965 edition of The Spectator.
Usage examples of "nanny state".
I remember Anson Guthrie remarking once that when he was young, Sweden was what he called a nanny state, but it got rid of that and nowadays people there are more free than in most countries, including North America.
I'm not being sentimental: I am aware that this happy family snapshot was just that, a snapshot, and an unedited video would have captured a sulk from Tom before we arrived at the pool (hates swimming with us, wanted to go round to Jamie's) and a rant from David after (I refuse the kids permission to buy crisps from the vending machine because we're going straight home for lunch, David is compelled to tell me that I am a living embodiment of the Nanny State).