* Euro gains, in tandem with higher-risk currencies, stocks * Relief at German Constitutional Court ruling * But euro still vulnerable; ECB on Thurs seen a risk * Aussie gains on data; Swedish crown up on policy decision By Jessica Mortimer LONDON, Sept 7 (Reuters) - The euro rose against the dollar on Wednesday on relief the German Constitutional Court did not uphold lawsuits aimed at blocking participation in euro zone bailouts, while it was also buoyed in tandem with high-yielding currencies and stocks. However, it was vulnerable to further selling as Germany's court also said parliament must have a bigger say before such aid is granted, making a solution to the euro zone debt crisis more cumbersome. The euro was up 0.6 percent against the dollar at $1.4085 . Traders said it had support above $1.40 after failing on Tuesday to make a sustained break below there, but said investors were still inclined to sell on rallies, leaving open the door to a drop towards the July 12 low at $1.3837. "The Constitutional Court ruling is probably just one trouble less for the market rather than a potential boost for the euro," said Roberto Mialich, currency strategist at Unicredit in Milan. "A break lower to $1.38 is still a high possibility and the charts clearly show that more upside is needed to stem selling pressure," he said, adding for this it would need to rise to around $1.4250-$1.4300. The German ruling highlights political difficulties in reaching a solution to the euro zone periphery's debt crisis, while concerns remain that weak growth may prevent indebted countries fulfilling plans to cut their deficits. Analysts also said the euro would be vulnerable ahead of an interest rate announcement from the European Central Bank on Thursday. "At the moment there are more negative factors for the euro than the dollar, and we also have the ECB tomorrow where they are bound to be more dovish in their message," said Niels Christensen, currency strategist at Nordea in Copenhagen. A rise in equities, helped after better-than-expected ISM non-manufacturing PMI figures and data showing Australia's economy growing at its fastest pace in four years last quarter, nudged the euro up, but it stayed off a high of $1.4286 hit on Tuesday. Traders said it may soon sink back under its 200-day moving average around $1.4019. "The euro has to some extent been supported by slightly higher interest rates (in the euro zone), so any comments by (ECB President Jean-Claude) Trichet hinting at some form of easing would send the euro down towards $1.37," said Minori Uchida, senior analyst at Bank of Tokyo-Mitsubishi UFJ in Tokyo. The euro retained its hefty gains made against the Swiss franc on Tuesday after the Swiss National Bank shocked the market by saying it would enforce a limit of 1.20 francs to the euro by buying foreign currencies in unlimited quantities. It was last steady at 1.2067 francs. SWEDISH CROWN, AUSSIE RISE The Swedish crown rose to a three-month high of around 8.9444 per euro after Sweden's central bank said further monetary tightening would be postposned but did not signal any intent to cut rates, which some investors were speculating. Analysts said investors were increasingly seeing the Swedish currency -- along with the Norwegian crown -- as a safe alternative to the euro after the SNB curbed appetite for the Swiss franc. Commodity currencies also rose, with the Australian dollar up more than 1 percent at $1.0616 , buoyed by the Australian data. Its next resistance level was the 100-day moving average at $1.0650. The dollar index was down 0.7 percent on the day at 75.412. Against the yen, the dollar was down 0.6 percent at 77.13 yen , with the Japanese currency supported following the Bank of Japan's decision to keep policy on hold. Traders said some players had expected Japan may also ease after Tuesday's move by the Swiss National Bank to curb strength in its currency. (Additional reporting by Antoni Slodkowski in Tokyo; Editing by Toby Chopra, Ron Askew)

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