I'd like to do had a dynamic number of one start/end time pairs passed to a function as an input parameter. The function would then use the list instead of just one start, and one end time in a select statement.

CREATE FUNCTION [dbo].[GetData]
(
    @StartTime datetime,
    @EndTime datetime
)
RETURNS int
AS
BEGIN
    SELECT @EndTime = CASE WHEN @EndTime > CURRENT_TIMESTAMP THEN CURRENT_TIMESTAMP ELSE @EndTime END

    DECLARE @TempStates TABLE
        (StartTime datetime NOT NULL
        , EndTime datetime NOT NULL
        , StateIdentity int NOT NULL
        )

    INSERT INTO @TempStates
    SELECT StartTime
        , EndTime
        , StateIdentity
    FROM State
    WHERE StartTime <= @EndTime AND EndTime >= @StartTime

    RETURN 0
END