"I have great respect for the court and will not dole out advice to an independent body," ECB executive board member Jörg Asmussen told the mass-circulation daily Bild in an interview.
"But generally speaking, no institution operates in a vacuum. If the bond purchase programme has to be scrapped, that would have substantial consequences," Asmussen said.
Germany's Constitutional Court is to examine this week whether the ECB's "big bazooka", or Outright Monetary Transaction (OMT), is compatible with the country's Basic Law.
Ever since the ECB unveiled the scheme to buy up the sovereign debt of the euro area's most debt-wracked members last summer, fears of a break-up of the single currency have indeed receded.
Europe's storm-battered financial markets have enjoyed a period of relative calm, without a single OMT ever being carried out.
Nevertheless, like many of the ECB's emergency anti-crisis measures, the OMT has its critics -- both in the pro-euro and anti-euro camps -- who claim it is unconstitutional.
And the Karlsruhe-based court -- which already threw out similar objections to the eurozone's bailout mechanisms -- will now turn its attention to the OMT. During the two-day hearing on Tuesday and Wednesday, both Asmussen and Bundesbank President Jens Weidmann take the stand.
Weidmann has been among the vocal critics of the OMT scheme and so the constitutional court hearing could prove a showdown between the ECB and the Bundesbank, experts say.