Don't they use checks and balances? That's my answer.
executive
they can limit the legislative branch's power by veto their law
The judiciary can hold the Executive branch to account for its actions; it is a system of 'checks and balances' that ensure no branch of government has too much power.
So that one branch is not stronger than tthe other.
This question isn't specific enough. In order to get the best answer you need to define who "they" are.
In the United States, the Senate is one of the two houses that make up the Legislative Branch, aka Congress. According to the system of Checks and Balances, the Legislative Branch can limit the power of the Executive Branch through two methods: it can override a President's veto with 2/3 majority vote (meaning the bill will become law anyway without President's signature), or it can remove an unsatisfactory Executive Offical from office, because it has the power of impeachment, and it also tries impeachment cases. The Legislative Branch also has some power over the Judicial Branch because it confirms judicial appointments.
The power of the Executive branch is to enforce laws enacted by the Legislative branch.
Power maintained by the legislative branch over the executive branch is to help keep the executive in check. The legislative has the power to veto executive polices and can also impeach the president and other executive officers.
The power of the executive branch is enforce the laws,the power of the legislative branch is to make laws, and the power of the judicial branch is to interpret the laws
executive branch.
The President is the power of the executive branch. He appoints all of the leaders of the 15 departments.
Executive branchIn the United States government, the President (the head of the Executive Branch) has the power to veto legislation.