More than a hundred Conservative MPs have written to the Prime Minister - via the Daily Telegraph - demanding he resist the transfer of certain justice and policing powers to Brussels. So, another rebellion brewing, indicating division in the Tory ranks and threatening to destabilise David Cameron? Er, no, actually.

This is no belligerent broadside from the intransigent europhobic ultras. The names on the list include the usual and predictable suspects. Bill Cash is on there, so are Edward Leigh and Bernard Jenkin. But there are also new MPs from the 2010 intake - Chris Skidmore, Charlotte Leslie, Priti Patel, Kwasi Kwarteng, Dominic Raab, Charlie Elphicke (those last two being, apparently, the organisers of the thing). These are thrusting, ambitious types, tipped for big things in the future. They are not the sort to casually blot their copy books with ill-judged campaigns that might embarrass their most vital potential patron in Downing Street. A key signatory is George Eustice, a former press spokesman for Cameron and, in a past political life, a candidate for Ukip. He represents the overlap between the new MPs' raw eurosceptic instincts and their preferences not to come across as troublemakers.

Many of the signatories would only have put their names to this missive with reassurance that no harm to their future careers would be done by it. Indeed, it is not so far-fetched to suppose that the Tory whips and Number 10 are supremely relaxed about this manoeuvre. Supportive, even.

Why? The move the letter urges is not as demanding as it might seem. In most respects, "repatriating" powers from Brussels would require a difficult negotiation, re-opening past treaties, building alliances with like-minded governments elsewhere in Europe and offering concessions to secure a deal. That much Cameron found to his cost when demanding special protection for the City in December (in a way that amounted to a repatriation of certain regulatory powers). The answer was an unequivocal and swift "no".

But what the Telegraph letter refers to is the exercise of an "opt out" - which just to confuse matters is really the selective exercise of an "opt in" - with regard to combined European Justice and Home Affairs (JHA) policy. This is a fast-growing body of European law to cover cooperation between different national jurisdictions on matters such as extradition, arrest warrants and, most controversially, asylum and immigration. The theory behind integrating policy in these areas is that migration issues and crime are plainly borderless enterprises, so EU policy should evolve to reflect that fact.

The idea of ceding authority over aspects of the British justice system to EU institutions is anathema to the Tories. It didn't much appeal to the last Labour government either and the UK negotiated the right to "opt in" to measures in this field on an ad hoc basis. Under the Lisbon Treaty, Britain continues to be able to pick and choose when it comes to participation in JHA measures but not forever.

After the 1 December 2014, the separate JHA "pillar" of EU policy will be merged with the bulk of EU practice and so decisions made in that area will be approved or rejected by a qualified majority vote in the European Council - the regular Brussels summits of EU leaders. In other words, from that moment onward, there would be no veto option. Six months before that happens, the UK has to decide whether it is in or out of the whole JHA integration process. No more pick 'n' mix.

So the deadline is June 2014. Now it so happens that integration in the JHA field is quite popular with the police. It has helped track down terrorists and serious organised criminals hiding out in other European countries. It has enabled the smashing of European paedophile rings. It is also popular with the Liberal Democrats. When challenged on his Europhilia in the 2010 election, Nick Clegg extolled the virtues of the European arrest warrant as an example of something practical and useful that the EU does.

But there are clearly problems too. British authorities complain about the cost and administrative hassle of dealing with mountains of extradition requests from other EU jurisdictions for petty offences - the Polish plumber who turns out to be wanted on a shoplifting charge in Krakow and has to be shipped there at UK expense. There is also understandable squeamishness about limiting British powers to intervene when citizens are hauled before other countries' courts.

Anyway, the pros and cons argument hardly matters because there is simply no way David Cameron could get away with signing up to the fully integrated JHA package even if he wanted to. It would probably require a vote in parliament and could easily and realistically be presented as a substantial cession of sovereignty, which, under the 2011 European Union Act would trigger a referendum.

Bear in mind also that the June 2014 deadline coincides with elections to the European parliament. The last time around, Ukip came second in the national vote.

What the signatories to the Telegraph are asking is that Cameron refuse to exercise his full JHA opt-in, thereby, at a stroke, "repatriating" a bunch of powers from Brussels. It is pretty hard to imagine him doing anything else. The Lib Dems won't like it, but a year before a general election it is just as hard to imagine them ramping up their anti-Tory rhetoric on the basis that they want to make it easier for British citizens to languish in Bulgarian jails as, no doubt, the eurosceptic press will depict their position.

This may come across as an arcane technical process, but it is definitely exercising strategic minds on both sides of the coalition. There is no particular reason why a bunch of Tory MPs should suddenly today decide to urge the Prime Minister to do something in 2014, which, in any case he probably means to do. Unless, of course, there is an appetite in the party for putting down markers, staking out policy territory, in case the Lib Dems start feeling a bit cocky about their influence over European policy. This is not a manoeuvre against Cameron, it is a shot across Nick Clegg's bow and I don't suppose Number 10 is unhappy about that at all.