Expertise + Improved Expertise

[Big Orc Man]

If you're immobilized crouching behind a tower shield, you're still crouching behind a tower shield.

Want to break an IE'er?  Bust out some high Taunt!

[Moon]

Or, if it's a pvp situation, hold person and roleplay taking away their shield while they are paralyzed! Or cut off the hand holding the shield. That solves the whole IE working despite being immobilized mechanics concern :)

[Egon the Monkey]

The first isn't possible, and the second is PC mutilation which both requires the PC to have been subdued and the presence of a DM.