lobbying client

游说客户 （lobby就是做说客，一般政治上比较多，也有职业商务型的，美国有专门的游说公司）

I have a problem in understanding one of the terms in American law concerning lobbying. That is,a client and a lobby company should not reach an agreement in payment on the premise that the company should succeed.
我在理解一条有关游说的美国法律规定时有个问题，即客户和游说公司不得以成功为前提达成付款协议。