quality:correction, information:highlighting
Modern Constitutional doctrine: International Shoe doctrine

What constitutes sufficient "minimum contacts" has been delineated in numerous cases which followed the International Shoe decision. For example, in Hanson v. Denckla, the Court proclaimed the "unilateral activity of those who claim some relationship with a nonresident cannot satisfy the requirement of contact with the forum State. The application of that rule will vary with the nature and quality of the defendant's activity, but it is essential in each case that there be some act by which the defendant purposefully avails itself of the privilege of conducting activities within the forum State, thus invoking the benefits and protection of its laws."