By Annika Breidthardt KARLSRUHE, Germany (Reuters) - The European Central Bank vigorously defended its bond-buying program in a German courtroom on Tuesday, arguing that the scheme many credit with saving the euro from collapse was within its mandate and had not spawned unlimited risks.

The European Central Bank on Tuesday defended its controversial bond purchase scheme, credited with pulling back the eurozone from the brink of collapse last year, in front of the Germany's highest tribunal, the Constitutional Court. Critics of the ECB's "Outright Monetary Transactions" (OMT) have asked the court to examine whether the scheme is in line with Germany's Basic Law or whether it breaches the central bank's mandate.

The eurozone's battered economies are slowly emerging from a crippling recession with growth expected to return by the second half of 2013, EU Economic Affairs Commissioner Olli Rehn said on Tuesday. Rehn was in The Hague, where he met Liberal Prime Minister Mark Rutte as well as Finance Minister and Eurogroup finance chief Jeroen Dijsselbloem, to discuss the Commission's budget reform recommendations for the Netherlands. "The euro area's economies are slowly emerging from the recession," an upbeat Rehn told journalists at a press conference.

The European Central Bank defended in Germany's highest court Tuesday a controversial bond purchase scheme that is credited with pulling back the eurozone from the brink of collapse last year. The Constitutional Court has been asked by critics of the ECB's "Outright Monetary Transactions" to examine whether the scheme is in line with German law or whether it breaches the central bank's mandate. The plaintiffs, a diverse group of German politicians, lawyers and citizens, argue the ECB is creating risks for German taxpayers that their elected representatives cannot control.