A double from Luther Burrell and one try apiece for Vasily Artemyev, Mike Haywood and 23-year-old Lawes put Northampton into a commanding 37-3 lead to leave their opponents staring down the barrel.
But a superb 16-minute spell which saw Jonny Arr, Josh Matavesi, Josh Drauniniu and Ollie Hayes all crash over pulled the score back to within a converted try but Saints held out to maintain their 100 per-cent record after four games.
Leicester Tigers suffered their first home defeat for 11 months to Harlequins in a rematch of last season's Premiership final - Quins coming out 22-9 winners.
Tom Williams scored the only try of the game and Danny Care also chipped in with a drop goal for Quins while England No.10 Toby Flood hit three penalties to continue his good form with the boot.
The maturing Freddie Burns continued to enhance his burgeoning reputation with a 19-point haul for Gloucester who won 29-22 at home to London Wasps.
The 22-year-old was flawless with the boot - another performance that boosts his hopes of featuring for England during the autumn internationals.
James Simpson-Daniel scored a fine solo effort and Sione Kalamafoni also got in on the act for the Cherry and Whites while Wasps struck back through Elliot Daly.
And London Irish beat Bath to pick up their first points of the season with a 29-22 victory.
Jonathan Joseph and Kyle Eastmond both scored tries for Irish and Bath respectively while it was 19 points from the boot of Steven Shingler that made the difference for the Exiles.