Totnes MP Sarah Wollaston is the region's most vocal parliamentary opponent to Lord Justice Leveson's proposals for independent self-regulation of the Press.
Writing for the Western Morning News, in a piece to appear on Monday on the day of a House of Commons debate on the Leveson report, Dr Wollaston argues that it becomes "all too easy" for the Government to restrict press reporting once the regulator is written into law.
She said: "It is right that we should be wary. Any compulsion to join a regulator would amount to state regulation, threatening free speech and democracy and that would be a high price to pay."
David Cameron voiced "serious concerns and misgivings" about legislative action in the immediate aftermath of the report's publication on Thursday.
While Justice Leveson condemned the "culture of reckless and outrageous journalism" that dominated sections of the national press, the Prime Minister said the industry should be given "a limited period of time" to show it could get its house in order.
The comments put him on collision course with Deputy Prime Minister Nick Clegg and Labour leader Ed Miliband, and drew criticism from victims of the phone hacking scandal and press intrusion. A new watchdog would be given the power to require prominent apologies and impose fines.
Regional newspapers make a contribution to their communities that is "truly without parallel", Justice Leveson said, arguing that the criticisms should not be applied to local print journalists.
Mr Cameron's caution has won support from Dr Wollaston, who was elected in 2010. She writes: "Cameron is right not to rush to accept Leveson, however reassuring and wise he may appear. We need a full debate about the wider implications.
"The British Press may have enjoyed the longest pub crawl in history through last chance saloons but they have also protected our freedoms, entertained and informed us.
"If they are over-regulated we will simply drive more people to seek their scandals from online sources with almost no accountability at all. If newspapers become irrelevant who will buy them at all?"
Dr Wollaston, a former GP on Dartmoor, is critical of "disturbing practices" within the industry and "cultural attitudes amongst certain editors" that allowed illegal activity to take place. She also believes the principles behind the proposals are "sensible".
But she writes: "Leveson's most controversial recommendation is for legislation to recognise the new self-regulatory body. The question is whether this represents statutory regulation of the Press.
"Once that is written into law it is all too easy for the lines to be re-drawn to regulate what the Press can or cannot say or to exclude those whose views are unsympathetic to the Government of the day.
"Whilst Leveson explicitly states that he does not feel this would be the case and also suggests that we could legislate for the independence of the Press, it should concern us that once a line has been crossed to 'underpin' the regulator in law, it may result in a press that is directed or restricted."
Culture Secretary Maria Miller yesterday insisted the "principles" of Justice Leveson's blueprint can be met without giving it statutory backing.
But Gerry McCann, father of missing Madeleine McCann, said legal backing for any new system was the "minimum acceptable compromise for me and for many other victims".