By our constitution, the president is the executive. He is in charge of the day-to-day operations of the entire federal government. Of course he can issue orde

By our constitution, the president is the executive. He is in charge of the day-to-day operations of the entire federal government. Of course he can issue orders. They don't even need to be fancy signed documents. He can simply tell his employees what to do. Any method of communication should work, no matter how silly. The problem you might be looking for is that congress has granted rule-making authority to agencies that are part of the executive branch and thus under control of the president. This effectively allows the president to make law.