The Justice Department has concluded that the Obama administration can lawfully pay the community group Acorn for services provided under contracts signed before Congress banned the government from providing money to the group.---But the group has become a prime target for conservative critics, and on Oct. 1, President Obama signed into law a spending bill that included a provision that said no taxpayer money — including money authorized by previous legislation — could be “provided to” the group or its affiliates. A Housing and Urban Development Department lawyer asked the Justice Department whether the new law meant that pre-existing contracts with Acorn should be broken. And in a memorandum signed Oct. 23 and posted online this week, Mr. Barron said the government should continue to make payments to Acorn as required by such contracts. The new law “should not be read as directing or authorizing HUD to breach a pre-existing binding contractual obligation to make payments to Acorn or its affiliates, subsidiaries or allied organizations where doing so would give rise to contractual liability,” Mr. Barron wrote. The deputy director of national operations for Acorn, Brian Kettenring, praised Mr. Barron’s decision.