The US Department of Justice (DoJ) has approved Oracle’s proposed acquisition of Sun Microsystems for $7.4 billion. Oracle said that the DoJ has also waived the 30-day waiting period under the Hart-Scott-Radino Act.

Earlier, Oracle said it is expecting to complete the deal in August. The DoJ couldn’t give the approval after an initial investigation and has further extended the investigation into the deal. It has asked the companies to provide additional information related to the licensing of Sun’s Java software.

At that time, Dan Wall, an attorney with Latham & Watkins who counsels Oracle, said: “All that’s left is one narrow issue about the way rights to Java are licensed that is never going to get in the way of the deal.

The deal was originally announced in April, shortly after IBM has abandoned its bid to buy the software developer and hardware manufacturer.

As per the planned transaction, Oracle has agreed to buy Sun Microsystems’ shares for $9.50 each.

Sun Microsystems’ stock holders have approved the transaction on July 16, 2009. Closing of the transaction is subject to certain conditions, including clearance by the European Commission, the company said.