Freedom of speech. Courts have ruled that citizens have the right to group and petition to Congress to listen to a specific issue or more (redress of grievances). That has evolved into lobbying groups that are funded by corporations, organizations, unions, etc.<p>And courts have ruled that money = speech and thus government can&#x27;t regulate that either.<p>You can read more here:<p><a href="http:&#x2F;&#x2F;www.investopedia.com&#x2F;articles&#x2F;investing&#x2F;043015&#x2F;why-lobbying-legal-and-important-us.asp" rel="nofollow">http:&#x2F;&#x2F;www.investopedia.com&#x2F;articles&#x2F;investing&#x2F;043015&#x2F;why-lo...</a>