[plu]

Will halohydrin formation always occur with the hydroxide attaching to the more substituted carbon, regardless of the fact that the more substituted carbon is more hindered to S_N2 attack?  For example, the reaction of 1-methylcyclohexene with Br₂ in H₂O will result first in a bromonium intermediate, then attack by a water molecule at C1.  Will this reaction result in the production of 1-methyl-2-bromocyclohexanol even though C2 is less hindered than C1?

[wereworm73]

Hmmm...Doesn't the halonium ion resonate and cause a stronger partial + charge on the most highly substituted carbon bonded to the halogen?  With a tertiary carbon, I think the partial charge might be strong enough to offset the additional steric hindrance, and the water molecule that attacks the carbon to leave behind the OH group is only a weak nucleophile...It doesn't fit the profile for a classic S_N2 reaction. 

[movies]

It's the same argument that you use to explain any Markovnikov addition process.  The carbocation structure is more stable when the cation resides on a more substituted carbon atom, so more stability leads to ultimately more positive charge on that carbon and therefore more electrophilicity.