I can. And although I find this objectionable, it's not clear that it violates the constitution.
In the US Supreme Court decision in the case DELAWARE V. PROUSE, 440 U. S. 648 (1979), it was found that an officer cannot pull over a lone vehicle to merely check the driver's/vehicle's license or registration.
However, the court stated that "The holding in this case does not preclude Delaware or other States from developing methods for spot checks that involve less intrusion or that do not involve the unconstrained exercise of discretion. Questioning of all oncoming traffic at roadblock-type stops is one possible alternative." http://supreme.justia.com/us/440/648/case.html#663
Though not a specific ruling on the constitutionality of roadblocks, the suggestion is present that the court would rule in that manner were it presented as a case before the court.
Note however, that a police roadblock cannot be set-up "randomly," they must be pre-warned (such as public posting in a newspaper or on a police department website) and adequately posted as being such when you approach it.
In another court case, evidence found after searching a car that exited a highway to avoid a roadblock was suppressed, as the police had no reason to pull the vehicle over other than the "suspicious" act of exiting the highway to supposedly "avoid" the roadblock.
Obviously, the best thing to do is to avoid driving when there is a chance you might be above the limit... unless you want to be the first to take a case to the Supreme Court to have the rule on the constitutionality of the practice.