President Obama and congressional Democrats are pressing to increase the federal minimum wage to $10.10 an hour. Here are nine reasons why that's a bad idea.

1. It's a big country. The costs of living, especially housing, vary widely in America from state to state and city to city. If the point of raising the minimum wage is to provide a "living wage," why should the minimum wage in low-cost areas such as Texas or Oklahoma be the same as in high-cost areas such as San Francisco or Manhattan?

2. The states are already taking care of it. Twenty states and the District of Columbia already have minimum wages higher than the current federal minimum of $7.25 an hour.

3. Private industry and the free market are already taking care of it. Even low-skill, entry level positions in many areas already pay higher than minimum wage.

4. As an anti-poverty tool, it is a blunt instrument. A post by David Henderson cited by the chairman of the Harvard Economics Department, Greg Mankiw, points out that a lot of minimum wage earners are second or third-job holders in households with other income. That could include a teenage summer employee whose parents both have jobs. Other minimum wage workers may include retirees with income from savings and Social Security who own their homes mortgage-free.

5. It's not clear that it's constitutional. The Supreme Court, in its opinion in the 1923 case Adkins v. Children's Hospital of District of Columbia, made a strong argument that a minimum wage was a violation of the constitutionally guaranteed freedom of contract embedded in the Fifth Amendment's language about due process and the deprivation of liberty and property: "To the extent that the sum fixed exceeds the fair value of the services rendered, it amounts to a compulsory exaction from the employer for the support of a partially indigent person, for whose condition there rests upon him no peculiar responsibility, and therefore, in effect, arbitrarily shifts to his shoulders a burden which, if it belongs to anybody, belongs to society as a whole." The Court later, in the 1937 case West Coast Hotel v. Parrish, reversed Adkins by a five to four margin. But maybe the court was right the first time around.

6. Even if the freedom of contract isn't protected by the Constitution, it's a natural right that should not be infringed. As President Kennedy put it in his inaugural address, "the rights of man come not from the generosity of the state but from the hand of God." If two free people want to enter into a voluntary, consensual agreement that doesn't infringe on anyone else's rights, why should the government stop them? If someone wants to work for $5 an hour, and someone wants to hire that person for that much, and no one is forcing either one of them to enter into the agreement, by what authority does government step in and stop them?

7. It would eliminate jobs. Ordering businesses to pay entry-level workers more will make them hire fewer of them, and consider replacing more workers with robots or computers. That's good if you are in the robot or computer business, but not so good if you are trying to combat unemployment. The nonpartisan Congressional Budget Office estimated that President Obama's proposed $10.10 wage, once fully implemented, "would reduce total employment by about 500,000 workers."

8. It would reduce the incentive for low-wage workers to get an education and move up to a higher-paying job. The lower the minimum wage, the more eager a minimum wage worker would be to enroll in a community college course at night, improve his or her skills, and apply for a higher-paying job. Making the entry-level jobs higher paying increases the risk that workers will get stuck in them for longer instead of moving on to something more rewarding.

9. It's a sneaky way to increase welfare spending and raise taxes. Raising taxes to spend more on welfare is a political loser. But raising the minimum wage puts money in the pockets of working poor people, at the expense of business owners (and of consumers who would pay in the form of higher prices). If politicians want to increase the earned income tax credit or other work-related welfare benefits, they should do the hard work of building political support for such policies, rather than choosing the roundabout approach of a minimum wage increase.