Now that it's obvious BP wasn't prepared for a worst-case scenario with its deepwater drilling in the Gulf of Mexico, the massive cleanup effort comes down to two questions:

How much will it cost to make communities whole again? And how do we make sure BP pays for all of it?

Innocent towns trapped in BP's viscous mess shouldn't have to pick up the tab for the historic screw-up of a multibillion-dollar company. Neither should taxpayers.

BP, the creators of this disaster and the subject of a criminal investigation, should keep writing checks until every pelican is squeaky clean, every marsh is bustling again with wildlife and every droplet of oil is gone.

To ensure that, Congress must lift the current $75 million federal liability cap - pennies in a spill this size - to $10 billion (or beyond) for any company that causes the pollution.

Officials, including the U.S. attorney general, believe the law can be made retroactive, because courts have been sympathetic to similar measures that aim to recover costs, not punish offenders. Also, if BP is found to have acted negligently or violated the law, the cap would not be in effect, anyway.

"Those who pollute should pay, and they should be unlimitedly responsible for their actions," said Sen. Robert Menendez (D-N.J.), the bill's chief sponsor.

Greater liability would force oil companies to think twice about risky drilling. Menendez believes the $75 million cap encouraged ecological gambling, because it was so low.

BP officials have said they will pay more than $75 million, but given BP's cover-its-assets mentality, the government would be crazy to accept its word. Exxon made huge profits in the aftermath of the Valdez disaster, but still disputed cleanup costs at every turn.

Oil industry officials say a $10 billion cap would force smaller companies to abandon deepwater drilling because insurance would become too expensive. Lee Fuller, of the Independent Petroleum Association of America, said oil companies might prefer a big increase in the 8-cent-a-barrel tax on oil that now goes to a trust fund to cover costs over $75 million. But it's doubtful that fund, currently about $1.6 billion, could generate enough money to pay for a massive spill, let alone two within a short period of time.

The lesson learned from BP is simple: If companies can't stop the gushing, clean up the mess and cover the costs when things go wrong, they shouldn't be drilling.