Not so. The courts have held that "treason, felony, or breach of the peace" covers all criminal offenses. Nowadays, a privilege against arrest in a civil case is no great matter; but it was important in the early days of the Union, when imprisonment for debt was common.
In any case, the Capitol Police officers would have known the House was not in session; it's their job to know.
I wondered to whom the Capitol Police answer. It tuns out that the force is under a Board consisting of the Architect of the Capitol and the Sergeants-at-Arms of the two Houses. The Architect of the Capitol is a Clinton appointee (his term expires next year), but the Sergeant-at-Arms of each House was elected by the current membership.
I think you are incorrect but I will do further research. It may be different in different places and it also may be different with Federal Law.But regardless the point I was trying to make was that Kennedy made the statement to keep from being arrested and I do believe that,why else would he have said it other than to get out of being arrested or as an excuse.
If you have some information on where the courts have ruled that I would appreciate you giving it to me so I could look it up, thanks.