9. Laws? Abide By It
The POTUS is also a citizen of the United States. They are subject to all of the laws that any other person would be. If a President breaks the law they can be impeached by the House and Senate.
10. Make Same-Sex Marriage Illegal
In June of 2015, SCOTUS ruled that gay marriage is a constitutional right. In order for it to change, there would need to be a challenge in lower courts bumped up to the SCOTUS once again to make another ruling with different members.
11. Change The Tax Code
A congress needs to pass the Tax Reform in order for it become a law. Even then it may take years before it takes effect.
12. President Cannot Accept Expensive Gifts
POTUS cannot accept expensive gifts from other world leaders and dignitaries. Most of the gifts are sent to the National Archives, anyway.
