Groups that seek to influence public policy for the specific and often exclusive benefit of their members or of people with similar interests are known as private interest groups, often called "special interest groups" by the media and in casual use.
We use the term "private" instead of "special" for two reasons. First, the term private points us to the nature of the objectives these groups seek to fulfill, which are policies that provide benefits targeted to specific individuals and groups. Interest groups made up of financial institutions, for example, promote policies that further their interests, like preventing legislation that might limit the fees they charge for financial services.
We also use the classification "private interest groups" because the term "special interests" has acquired a negative political connotation. Political partisans often use the term in a derogatory way to attack their opponents, regardless of party or ideology. If we're in a political race, my supporters are friends, voters, and concerned citizens; your supporters are "special interests," implying that your supporters somehow work against the (in this context, undefined) public good.
Some of the goals that private interest groups pursue may impose costs on other private groups while benefiting society as a secondary or unintended consequence. For example, when insurance companies contributed to efforts to place warning labels on cigarette packages, they were not directly concerned about public health per se. They sought to lower the cost of healthcare claims by lowering the number of cigarettes sold, threatening the sales of cigarette manufacturers. Yet insurance companies' efforts to lower their costs may have benefited public health.
So, the pursuit of private interests need not undermine the common welfare. Indeed, just as the pursuit of private economic self-interest benefits the economy as a whole, so also the pursuit of political self-interest is often thought to be a good thing for the political system overall, even if some specific policy outcomes seem undesirable.
A persistent belief in U.S. political culture, which also runs deep in Texas, holds that competition among self-interested individuals and groups is good for the health of society overall. From the founding of the United States, it has been widely argued that competition fueled by self-interest is a condition that successful democratic institutions must recognize, accommodate, and even use to produce consensus and stability. This pluralist interpretation of democratic politics reflects the perception that the process by which citizens and interest groups freely express their desires before the government is more important than specific policy decisions. It also reflects the often implicit expectation that in the long run good ideas (or policy) push out the bad as groups compete to promote their own interests.