Describe the methods that established professional sports leagues

1)Describe the methods that established professional sports leagues have  used to thwart the success of new rival leagues in their sport. Provide  evidence to support your response by referring to at least one the  following cases: North American Soccer League v. National Football League; Philadelphia  World Hockey Club, Inc. v. Philadelphia Hockey Club, Inc.; United  States Football League v. National Football League; American Football  League v. National Football League; Hecht v. Pro Football.

2) Describe  the European system of promotion and relegation as it relates to its  professional sports system. Do you think a similar system should be  implemented for the American professional sports leagues?  Have there  been any attempts to do so?  Could such a system work?  Why or why not?  Identify the pros and cons of each position. Describe the legal  considerations that would affect such a decision.