Mentioning Competitors in Your Ads

Dear Reader:

1. Within the limits of the law, a person should be able to mention their competitors in an ad.
2. Within the limits of the law means you must not defame (libel or slander) them.
3. Even if the words are spoken in the ad, the fact that the words are permanent (i.e. the ad has been recorded on DVD or in another form) makes it libel and not slander.
4. I believe you can for example say than your product is better than your competitor's.
5. You may even be able to say yours is healthier since it is relative and does not say that theirs in unhealthy.
6. The problem arises when you attribute negative, hazardous or dangerous attributes to your competitor's product.
7. For example, if you are going to claim in an ad that your competitor's product causes blindness or cancer or impotence or obesity or hypertension, you must have some (scientific) proof of that. If you have proof, then you can fall on the defence of Justification (a fancy word for truth) if they sue you for defamation.
8. But defamation is not the only complaint your competitor could have against you.
9. There is an area of law called economic torts. One such is Tortious (Wrongful) Interference with Business Relationships, where Party A's conduct or statement prevents Party B from successfully building or retaining business relationships. An example would be where your false or unsubstantiated statement about a product causing cancer causes the producer to lose their present and prospective clientele. 
10. Just as with defamation, a person who has suffered an economic tort by your action can sue you for damages.
11. In sum, beyond making damaging comments about your competitor in your ad, there is very little they can do. If your statement is merely comparative, it may well be seen in law as a mere 'puff', without more.

(I apologise for not coming back earlier. I took my eyes off this space because I had not had a question in a while.)