The watchdog considered complaints about two TV ads and one press ad, all created by McCann Manchester, which focused on comparing the price of a basket of goods from Aldi with its equivalent at Asda, Morrisons, Sainsbury's and Tesco (or specifically Morrisons in the press ad).
The comparison in each case was between a basket of branded goods and the equivalent own-label products in Aldi – meaning they suggested a saving of as much as 38% (£33.04 compared to £53.35).
Aldi said the ads were only meant to be about the goods shown and that it had demonstrated this with small print shown on screen and at the bottom of the print ad.
But the ASA ruled the ads gave the impression that a typical customer could expect to make savings on this scale if they switched their entire shop from a 'big four' retailer to Aldi.
It said that in actual fact, the typical saving would be smaller, because the average 'big four' shopper would buy a mix of branded and own-label goods, with the latter generally much closer in price to Aldi’s products.
In another point of contention, Aldi said it was fair to compare its own range to brands because they were closer to them in quality than to the own label ranges of the 'big four' – basing this on the product specifications.
But the ASA said that, whether or not this was true, the ads had focused only on price, not quality – so in order for the claims to be allowed, the comparison basket should have contained a mix of branded and own label goods.
The watchdog ruled that the ads breached Code rules on misleading advertising, comparisons with identifiable competitors and price comparisons and ordered them to not be used again in the form complained of.