Make it illegal for an elected official (President of The United States, House of Representatives, and U.S. Senate) or Supreme Court Justice to vote, sign, or judicate a Bill, when he/she has a financial gain or lose via investment, due to the vote.
Justification: Many times an elected official for example, will vote for a bill in support of oil companies, if they have stock in that industry. Another example, an elected official may vote for a bill that helps green energy, while they have stock in that industry.