In a global competitive business, comparative advertising has substantial influence on consumer behaviour. The comparative advertisement and puffing is legally permitted as long as the comparison is honest and based on verifiable feature and not aimed to and/or extends to cause direct or indirect disparagement of competitor’s goods and which does not take unfair advantage of or in any way be detrimental to the reputation of the competitor’s product.
Omesh Puri in his article http://www.mondaq.com/article.