President Barack Obama continues to treat the Affordable Care Act as if it is an island beyond the territorial waters of the Constitution. Again this week, he made substantive changes to a law passed by Congress without consulting lawmakers.

The president issued an executive order delaying until 2016 implementation of the employer mandate affecting businesses with between 50 and 99 employees.

It was the second time Obama has pushed back the mandate, which was supposed to go into effect on Jan. 1. Previously, the administration also relaxed requirements on large employers, and allowed for selective postponement of the individual mandate.

The White House explains the delays are designed to give employers more time to adjust to Obamacare's requirements and claims it has the authority to offer such "transitional relief."

That's true only when a law leaves room for discretion. With Obamacare, there is no ambiguity in the language. It says the mandates "shall apply" after Dec. 31, 2013.

Past presidents — most recently George W. Bush — have refused to implement laws they felt were unconstitutional, and they have leeway to do that while legality is being decided. But that's not the case this time; the administration successfully defended the constitutionality of Obamacare in court.

This latest delay appears to be primarily about politics. Democrats facing re-election this fall are worried about the impact of a new round of policy cancellations and premium hikes announced just before Election Day. Or worse, they fear businesses may lay off workers to get under the mandate's employee limit.

But Obama is hurting his own law, and likely the economy, with these serial rewrites.

The law was crafted to quickly get a large pool of people insured by Obamacare so that healthy policyholders would offset the cost of insuring the sick and elderly.

In addition, the projected cost of the Affordable Care Act was based on the various pieces of the law fitting together in the specified time frame.

With the implementation delays and carve-outs, there's no way to make accurate cost and enrollment projections.

Many small business owners object to the latest postponement, complaining they've already worked with their insurers, at considerable cost, to craft policies that comply with Obamacare.

The delay adds to their wariness of the law's impact.

"They're all ready to (meet the previous deadline) and now they're confused — so they don't want to make any decisions," Scott Lyon, vice president of the Small Business Association of Michigan, told The Detroit News.

Uncertainty is bound to affect hiring and staffing decisions.

Obama is right that the Affordable Care Act is not ready for prime time.

It needs changes that impose more reasonable deadlines and address the negative impact on employment and economic growth.

But the Constitution demands that many of those alterations be made by lawmakers, and not unilaterally by the president.

If there are legitimate reasons to delay the mandate, Obama should present them to Congress and ask its approval.

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