Angry scofflaws had better think before they spit.

Law enforcement is mulling a plan to use DNA samples to prosecute expec-torating hotheads who hock loogies on transit workers.

Brooklyn District Attorney Charles Hynes plans to discuss the high-tech technique — already employed in Boston and London — with the NYPD, his spokesman said yesterday.

“It’s something we are going to look into,” said spokesman Jerry Schmetterer.

From the beginning of the year through October, 145 bus and subway workers were spit on, officials said.

“It’s a positive step,” said John Samuelsen, president of TWU Local 100, the MTA’s largest worker union.

Assaults on bus drivers are up 20 percent from last year, while crimes against subway workers rose 16 percent in the same time period.