MORNING BID EUROPE-Brexit - via Crown or Commons?

* A look at the day ahead from European Economics and Politics Editor Mark John and EMEA markets editor Mike Dolan. The views expressed are their own.

LONDON, Jan 24 (Reuters) - So confident was it that Britain would vote to "Remain" in Europe, David Cameron's government omitted to spell out in its referendum legislation how the Brexit process would be started should Britons choose Leave. Six months later, the UK Supreme Court rules from 9.30 am (0930 GMT) on whether PM Theresa May has the right to use a so-called "royal prerogative" to invoke the Article 50 exit clause or must go through parliament. Most observers expect it to follow the High Court's existing verdict that it should be the latter -- an outcome which need not prevent May from triggering Article 50 as planned by end-March given the expected majority for that in the House of Commons lower house. Yet potential surprises include a ruling that the UK's devolved assemblies must give their approval too -- an outcome that could derail that timetable thanks to the current political limbo in Northern Ireland; or a possible referral to the European Court of Justice on whether Article 50 can be reversed once triggered.

Italy's constitutional court meets to discuss the merits of a new electoral law in a case that has major implications for when parliamentary elections might be called. The law will have to be changed regardless of the court's decision, but the judges observations will undoubtedly influence the debate. Calls for a major overhaul might complicate a push by some politicians, including former prime minister Matteo Renzi, for early elections in the first half of 2017. The law under review only covers elections for the lower house of parliament. However, it was drawn up by the former government in the belief that the Senate upper house would no longer be directly elected. A massive 'No' vote in a Dec (Shanghai: 600875.SS - news) . 4 referendum put paid to that, meaning parliament must now come up with a law that covers both houses. It is not clear when the court will reach a decision and when its findings will be published. It could take several days.

MARKETS AT 0755 GMT As markets begin to look more skeptically as the unfolding Trump presidency stateside, Tuesday puts Britain, Turkey and Italy back in the immediate spotlight. The UK Supreme Court ruling on whether parliament, and not just the sitting government, should have a say in triggering Brexit comes at 0930 London time. The likelihood is the court rules against the government appeal and says a Westminster vote is legally necessary. That's widely expected, most likely in sterling's price already and few believe it will either stymie or even delay the end-March deadline on invoking Article50 to leave the EU. Given the pound has typically strengthened on any indication of parliamentary oversight of Brexit, on the argument any delay or checks and balances 'softens' the final deal, then there may be still be a bias higher - as was the case last Tuesday on news PM May would allow parliament a say on the final Brexit deal. There is some outside speculation the ruling could indicate ongoing parliamentary scrutiny of the protracted negotiations, which may offer sterling a further positive. The wrinkles come with what it says about regional assembly involvement - Scotland and Northern Ireland in particular, both of whom argued they should have a say. While an unlikely ruling on regional assembly assent could well delay the Brexit timetables, some argue it may hasten a Scottish decision on a new referendum on secession and be a potential negative for the pound as a result. Either way, sterling has come off Monday's highs ahead of the ruling and is back below $1.25, while euro/sterling has nudged back above 0.86. On Turkey, the critical central bank interest rate decision comes at 1100 London time. A half-point rate rise is now widely expected as its best attempt to shore up the plummeting lira, but political pressure on the central bank to keep interest rates low remains the counterpoint and many in the market believe significantly bigger rate rises will be needed to turn the currency around. The lira has stabilized over the past week ahead of the decision and as the dollar has retreated more broadly, but it has weakened slightly this morning to 3.76/$. Italy's constitutional court, meantime, will hear the case on a disputed election law that's central to the decision on when Italy will hold its next general election. There's unlikely to be any firm decision today but there may be pointers on when the country may return to the polls and Italian 10-year government yields briefly touched a 6-week high on Monday. More broadly the dollar index, Treasury yields and oil prices have stabilized this morning, with Wall St stocks off slightly overnight, Asia bourses mixed and European stocks called slightly higher.

Upcoming events/data/ themes for market reports on Tuesday:

* Global flash manufacturing PMIs for Jan

* SKorea Jan consumer confidence

* Japan auctions 40-year JGBs

* Europe corp events: SAP (Amsterdam: AP6.AS - news) , IG (Frankfurt: A0EARV - news) , Phillips earnings, Dixons Carphone trading

* UK Supreme Court ruling on whether parliament needs to endorse triggering of Article 50 opening Brexit talks

* Italy constitutional court hearing on electoral laws

* SAfrica interest rate decision

* Turkey interest rate decision, Jan manufacturing confidence data

* Nigeria interest rate decision

* US Q4 earnings: Verizon (NYSE: VZ - news) , Lockheed Martin (Swiss: LMT.SW - news) , Travelers, J&J, Corning (Swiss: GLW-USD.SW - news) , Texas Ins, Kimberly Clark

* US Dec existing home sales

* US Treasury auctions 2-year notes

(Editing by Dominic Evans)