Courts consider a variety of factors to determine whether a likelihood of confusion exists. Similarity of the marks and the similarity or relatedness of the goods or services are the most important factors. Courts also look at things like the similarity of marketing channels, the strength (distinctiveness) of the original mark, intent to deceive, actual confusion, the level of sophistication of the target market, likelihood that a business might expand into other product lines and markets, among other things. In re duPont de Nemours is a leading case describing the kinds of things a court takes into consideration when deciding likelihood of confusion issues. No single factor is decisive.